theSLAYER

In Pokemon Alpha Sapphire, right after the player obtains the Dynamo Badge and heads east along Route 118,
Steven and Latios will approach the player, and they will fly off to Southern Island together to stop Team Aqua from capturing Latias.
The Latias will join the player's team, and it will be carrying a Latiasite.
In Pokemon Omega Ruby, after the player obtained the Mega Bracelet and speaks to Norman with the event Eon Ticket,
the player will take a ferry to Southern Island, and Latias can be encountered there.
This Latias will not be holding the Latiasite.

Both Latias will have the same level and moveset.
     Species   Latias   Nickname   (default, save lang)   OT   (recipient)   TID   (recipient)   Distribution   In-Game GiftAS / EncounterOR   Location   Southern Island   Dates   (Various)   PID   Chance of Shiny   Games   ORAS                                                                Lv. 30    Nature   Random   Ability   Levitate   Item   LatiasiteAS only    Moves   (ITALIC means Relearnable)   Heal Pulse   Dragon Breath   Mist Ball   Psycho Shift
  Format Ver.1.0.6-2, Post Updated Date:20180501_1431

This wonder card is sent from the Demo to your main Pokemon Sun or Pokemon Moon game.
 
WC 2041: Special Demo Version Star Piece Star Piece
        x 1 0x5B Thank you for playing the demo version! Please pick up your gift from the deliveryman in any Pokémon Center.             Pokemon Demo  |  Any Date  |  All 3DS: SM

In Pokemon Omega Ruby, right after the player obtains the Dynamo Badge and heads east along Route 118,
Steven and Latias will approach the player, and they will fly off to Southern Island together to stop Team Magma from capturing Latios.
This Latios will join the player's team, and it will be carrying a Latiosite.
In Pokemon Alpha Sapphire, after the player obtained the Mega Bracelet and speaks to Norman with the event Eon Ticket,
the player will take a ferry to Southern Island, and Latios can be encountered there.
This Latios will not be holding the Latiosite.

Both Latios will have the same level and moveset.
     Species   Latios   Nickname   (default, save lang)   OT   (recipient)   TID   (recipient)   Distribution   In-Game GiftOR / EncounterAS   Location   Southern Island   Dates   (Various Dates)   PID   Chance of Shiny   Games   ORAS                                                                Lv. 30    Nature   Random   Ability   Levitate    Item   LatiositeOR only    Moves   (ITALIC means Relearnable)   Heal Pulse   Dragon Breath   Luster Purge   Psycho Shift
  Format Ver.1.0.6-2, Post Updated Date:20180501_1438

This wonder card is sent from the Demo to your main Pokemon Sun or Pokemon Moon game.
 
WC 2040: Special Demo Version Stardust Stardust
        x 3 0x5B Thank you for playing the demo version! Please pick up your gift from the deliveryman in any Pokémon Center.             Pokemon Demo  |  Any Date  |  All 3DS: SM

In Pokemon X, the player will encounter Xerneas in Team Flare's Secret HQ, when the player tries to stop Lysandre from using the Ultimate Weapon to destroy all life.

This Pokemon has to be captured, in order to progress through the storyline.
If it was defeated or ran from, it would still be there, awaiting the player to begin the encounter again.
Additionally, even if the player attempts to fill all the slots in their PC, Box 31 was hidden from usage,
and is only unlocked after this Pokemon's capture.
     Species   Xerneas   Nickname   (default, save lang)   OT   (recipient)   TID   (recipient)   Distribution   In-Game Encounter   Location   Team Flare Secret HQ   Dates   (Various)   PID   Cannot Be Shiny   Games   X                                                                Lv. 50    Nature   Random   Ability   Fairy Aura   Item   None    Moves   (ITALIC means Relearnable)   Gravity   Geomancy   Moonblast   Megahorn
  Format Ver.1.0.6-2, Post Updated Date:20180501_2315

In Pokemon Y, the player will encounter Yveltal in Team Flare's Secret HQ, when the player tries to stop Lysandre from using the Ultimate Weapon to destroy all life.

This Pokemon has to be captured, in order to progress through the storyline.
If it was defeated or ran from, it would still be there, awaiting the player to begin the encounter again.
Additionally, even if the player attempts to fill all the slots in their PC, Box 31 was hidden from usage,
and is only unlocked after this Pokemon's capture.
     Species   Yveltal   Nickname   (default, save lang)   OT   (recipient)   TID   (recipient)   Distribution   In-Game Encounter   Location   Team Flare Secret HQ   Dates   (Various)   PID   Cannot Be Shiny   Games   Y                                                                Lv. 50    Nature   Random   Ability   Dark Aura   Item   None    Moves   (ITALIC means Relearnable)   Snarl   Oblivion Wing   Disable   Dark Pulse
  Format Ver.1.0.6-2, Post Updated Date:20180501_2317

This event was distributed to commemorate the launch of Pokemon Trading Card Game: Sun and Moon Expansion.
 
WC 599: Get a boost with a Bottle Cap! Bottle Cap
        x 1 0x00 Please pick up your gift from the deliveryman in any Pokémon Center.             Serial Code  |  Feb 03 - May 13, 2017  |  US&EU: SM Get a boost with a Bottle Cap! You received a Bottle Cap! Use it to
raise one of a Lv. 100 Pokémon's stats
to the max during Hyper Training.

From the period of January 31st to February 13th, there was a Global Mission to trade 1,000,000 Pokemon through the GTS.
When the mission succeeds, players will receive 2,000 FC.
If the player trades 5 times, with an account Game Synced with PGL, they will get 5 Rare Candies.
Furthermore, if 2,000,000 Pokemon was traded, a Friend ball will come bundled with the 5 Rare Candies.

The final count for the mission was 4,107,702 Pokemon traded.
 
WC 1604: Gift from the PGL Rare Candy
        x 5 0x38 This is a gift from the Pokémon Global Link! Please pick up your gift from the deliveryman in any Pokémon Center. Friend Ball           Serial Code  |  Feb 21 - Mar 31, 2017  |  US&EU: SM Gift from the PGL Thank you for participating in the
Global Mission!

This gift was given away to participants of the 2017 International Challenge (February Competition).
Participants were required to take part in at least 3 battles of the Online Competition, with a game synced game and account.

This event will then be given away via common password at a later time.
WC 1606: Mega Stone Gift Mawilite
        x 1 0x2C Thank you for playing Pokémon! Please pick up your gift from the deliveryman in any Pokémon Center. Beedrillite           Serial Code  |  Mar 07 - Apr 27, 2017  |  US&EU: SM Mega Stone Gift - Mawilite
- Beedrillite

From the period of February 28th to March 13th, there was a Global Mission to earn 250,000 Battle Points at the Battle Tree.
When the mission succeeds, players will receive 2,000 FC.
If the player earned 3 BP, with an account Game Synced with PGL, they will get 5 Rare Candies.
Furthermore, if 500,000 BP was earned globally, a Heavy ball will come bundled with the 5 Rare Candies.
The final count for the mission was 15,671,838 BP earned.
 
WC 1607: Gift from the PGL Rare Candy
        x 5 0x38 This is a gift from the Pokémon Global Link! Please pick up your gift from the deliveryman in any Pokémon Center. Heavy Ball           Serial Code  |  Mar 21 to Apr 27, 2017  |  US&EU: SM Gift from the PGL Thank you for participating in the
Global Mission!

This gift was given away to participants of the Regional Rumble: Kanto X Alola (2017 March Competition).
Participants were required to take part in at least 3 battles of the Online Competition, with a game synced game and account.

This event will then be given away via common password at a later time.
 
WC 1608: Mega Stone Gift Pidgeotite
        x 1 0x2C Thank you for playing Pokémon! Please pick up your gift from the deliveryman in any Pokémon Center. Steelixite           Serial Code  |  Mar 28, 2017 to ?   |  US&EU: SM Mega Stone Gift - Pidgeotite
- Steelixite

From the period of March 28th to April 10th, there was a Global Mission with the goal of collectively hatching 200,000 eggs.
When the mission succeeds, players will receive 2,000 FC. (failure resulting in 200 FC)
If the player hatched 3 eggs, with an account Game Synced with PGL, they will get 5 Rare Candies.
Furthermore, if 400,000 eggs was hatched globally, a Love Ball will come bundled with the 5 Rare Candies.
The final count for the mission was 14,503,078 eggs hatched.
 
WC 1610: Gift from the PGL Rare Candy
        x 5 0x38 This is a gift from the Pokémon Global Link! Please pick up your gift from the deliveryman in any Pokémon Center. Love Ball           Serial Code  |  Apr 18 - May 30, 2017  |  US&EU: SM Gift from the PGL Thank you for participating in the
Global Mission!

From the period of April 25th to May 9th, there was a Global Mission to harvest 3,000,000 Poké Beans from Poké Pelago.
When the mission succeeds, players will receive 2,000 FC.
If the player harvested 30 Poké Beans, with an account Game Synced with PGL, they will get 5 Rare Candies.
Furthermore, if 6,000,000 Poké Beans was harvested globally, a Level Ball will come bundled with the 5 Rare Candies.
The final count for the mission was 75,230,246 Poké Beans harvested.
 
WC 1612: Gift from the PGL Rare Candy
        x 5 0x38 This is a gift from the Pokémon Global Link! Please pick up your gift from the deliveryman in any Pokémon Center.
    Level Ball                     Serial Code  |  May 16 to Jun 29, 2017  |  US&EU: SM Gift from the PGL Thank you for participating in the
Global Mission!

From the period of May 30th to June 12th, there was a Global Mission for players to successfully hook 500,000 Pokemon or items (combined count) from rare (fishing) spots.
When the mission succeeds, players will receive 2,000 FC.
If the player have 3 successful hooks, with an account Game Synced with PGL, they will get 5 Rare Candies.
Furthermore, if there is a total of 1,000,000 successful hooks globally, a Lure Ball will come bundled with the 5 Rare Candies.
The final count for the mission was 1,228,170 successful hooks.
 
WC 1615: Gift from the PGL Rare Candy
        x 5 0x38 This is a gift from the Pokémon Global Link! Please pick up your gift from the deliveryman in any Pokémon Center.
    Lure Ball                     Serial Code  |  Jun 20 - Jul 30, 2017   |  US&EU: SM Gift from the PGL Thank you for participating in the
Global Mission!

The 3DS app Pokémon Bank accumulates Poké Miles over the duration of time that a Pokémon is stored on the Bank itself.
The player can choose to send Poké Miles or Battle Points to a chosen Gen VI or Gen VII game.

Since Gen VII games do not use Poké Miles, players are only able to send Battle Points to the selected games,
with the conversion rate of 1 Battle Point for every 10 Poké Miles.

While the card upload only has 10 Battle Points, it is possible to receive other amounts from Pokémon Bank.

In the games Pokémon HeartGold & SoulSilver, when the player interacts with Primo in the Violet City's Pokémon Center,
and gives the correct passwords, Primo will give the player an egg.

Officially, the passwords were only given for Japanese players via the Daisuki Club
(which the service for the passwords has since been defunct).
However, players can use external codeword generator to unlock the exclusive content.
As per any egg gift, it has a chance of being shiny when traded to another trainer with the correct TID/SID combo.

In the games Pokémon HeartGold & SoulSilver, when the player interacts with Primo in the Violet City's Pokémon Center,
and gives the correct passwords, Primo will give the player an egg.

Officially, the passwords were only given for Japanese players via the Daisuki Club
(which the service for the passwords has since been defunct).
However, players can use external codeword generator to unlock the exclusive content.
As per any egg gift, it has a chance of being shiny when traded to another trainer with the correct TID/SID combo.

In the games Pokémon HeartGold & SoulSilver, when the player interacts with Primo in the Violet City's Pokémon Center,
and gives the correct passwords, Primo will give the player an egg.

Officially, the passwords were only given for Japanese players via the Daisuki Club
(which the service for the passwords has since been defunct).
However, players can use external codeword generator to unlock the exclusive content.
As per any egg gift, it has a chance of being shiny when traded to another trainer with the correct TID/SID combo.

Using the Mystic Ticket received from events on their copy of Pokémon FireRed & LeafGreen, or Pokémon Emerald games,
players gain access to the Navel Rock, and get a chance to capture the Legendary Ho-Oh!
For players who rather not use the Mystery Gift to activate the event, simply use PKHeX's Event Flags > Research, and
For Pokémon FireRed & LeafGreen: Check Flag 2122 and 2123
For Pokémon Emerald: Check Flag 0315 and 2272
then proceed to add a Mystic Ticket into the Key Items of the Bag.

For Pokémon FireRed & LeafGreen, having the National Dex and Rainbow Pass may be required. More event flags here.

Using the Mystic Ticket received from events on their copy of Pokémon FireRed & LeafGreen, or Pokémon Emerald games,
players gain access to the Navel Rock, and get a chance to capture the Legendary Lugia!

For players who rather not use the Mystery Gift to activate the event, simply use PKHeX's Event Flags > Research, and
For Pokémon FireRed & LeafGreen: Check Flag 2122 and 2123
For Pokémon Emerald: Check Flag 0315 and 2272
then proceed to add a Mystic Ticket into the Key Items of the Bag.

For Pokémon FireRed & LeafGreen, having the National Dex and Rainbow Pass may be required. More event flags here.

In Pokémon Sapphire & Pokémon Emerald (when player selected Red at the TV at home when first entering Hall of Fame),
with the Eon Ticket (received from event in real life then from Norman in-game RS; received from Ruby & Sapphire via Record Mixing E),
players get to visit Southern Island and encounter the Legendary Latios.

Latios is the other Euo duo that wasn't roaming in the player's game, and it is holding the Soul Dew.

For players that wants to activate the event without Injecting the Mystery Event (EN/JP)RS/Gift Record Mixing (save)RS, read about the event flags here.

In Pokemon X & Y, after the player clears the Hall of Fame for the first time,
the first non-cave and non-Poke Radar wild encounter the player has would be with this Pokemon.

Upon encounter, this roaming Pokemon will immediately flee, before the player can even choose to use any moves.
After a total of 11 roaming encounters, this Pokemon will relocate to the Sea Spirit's Den, awaiting battle.
If the player defeats this Pokemon in the Sea Spirit's Den, the player would have to clear the Hall of Fame and do the 11 encounters again.
The legendary bird that the player encounters depends on the starter that the player chose at the beginning of the game.
Choosing Chespin, Fennekin or Froakie will lead to an encounter with Articuno, Zapdos or Moltres respectively.
     Species   Zapdos   Nickname   (default, save lang)   OT   (recipient)   TID   (recipient)   Distribution   In-Game Encounter   Location   Sea Spirit's Den   Dates   (Various)   PID   Cannot Be Shiny   Games   XY                                                                Lv. 70    Nature   Random   Ability   Pressure   Item   None    Moves   (ITALIC means Relearnable)   Agility   Discharge   Rain Dance   Light Screen
  Format Ver.1.0.6-2, Post Updated Date:20180502_1959

In Pokemon X & Y, after the player clears the Hall of Fame for the first time,
the first non-cave and non-Poke Radar wild encounter the player has would be with this Pokemon.

Upon encounter, this roaming Pokemon will immediately flee, before the player can even choose to use any moves.
After a total of 11 roaming encounters, this Pokemon will relocate to the Sea Spirit's Den, awaiting battle.
If the player defeats this Pokemon in the Sea Spirit's Den, the player would have to clear the Hall of Fame and do the 11 encounters again.
The legendary bird that the player encounters depends on the starter that the player chose at the beginning of the game.
Choosing Chespin, Fennekin or Froakie will lead to an encounter with Articuno, Zapdos or Moltres respectively.
     Species   Moltres   Nickname   (default, save lang)   OT   (recipient)   TID   (recipient)   Distribution   In-Game Encounter   Location   Sea Spirit's Den   Dates   (Various)   PID   Cannot Be Shiny   Games   XY                                                                Lv. 70    Nature   Random   Ability   Pressure   Item   None    Moves   (ITALIC means Relearnable)   Safeguard   Air Slash   Sunny Day   Heat Wave
  Format Ver.1.0.6-2, Post Updated Date:20180502_2001

After the player enters the Hall of Fame for the first time, a previously inaccessible area of the Terminus Cave becomes available to the player.
Zygarde solemnly awaits for the player to challenge it to battle.

As the other Zygarde forms was only introduced in Pokemon Sun and Moon,
players will not be able to perform form change with Zygarde.
     Species   Zygarde   Nickname   (default, save lang)   OT   (recipient)   TID   (recipient)   Distribution   In-Game Encounter   Location   Terminus Cave   Dates   (Various)   PID   Cannot Be Shiny   Games   XY                                                                Lv. 70    Nature   Random   Ability   Aura Break   Item   None    Moves   (ITALIC means Relearnable)   Crunch   Earthquake   Camouflage   Dragon Pulse
  Format Ver.1.0.6-2, Post Updated Date:20180502_2127

In Pokémon Ruby & Pokémon Emerald (when player selected Blue at the TV at home when first entering Hall of Fame),
with the Eon Ticket (received from event in real life then from Norman in-game RS; received from Ruby & Sapphire via Record Mixing E),
players get to visit Southern Island and encounter the Legendary Latias.

Latias is the other Euo duo that wasn't roaming in the player's game, and it is holding the Soul Dew.

For players that wants to activate the event without Injecting the Mystery Event (EN/JP)RS/Gift Record Mixing (save)RS, read about the event flags here.