Please give original credit to this link if posting elsewhere:
https://projectpokemon.org/home/files/file/2575-every-npc-in-game-trade-and-gift-pok%C3%A9mon/

Thanks!


Gen 1:

-Trades/Gifts in this Generation all have their IVs randomized.
-Trainer IDs are random for in-game trades.
-No unused Mew trade can be transferred to Gen 7 (Beedrill and Pidgeot can).

Gen 2:

-Spearow, Shuckle and the Stadium 2 gifts have random IVs.
-For the Stadium 2 Farfetch'd, you have to remove Baton Pass in order for it to be legal upon transferring to G7; Gligar can transfer with Earthquake retained on its moveset.
-Due to the Korean GS VC titles being unable to connect with other international copies (the original GBC carts reportedly can), the lowest legitimate levels possible for VC titles are 30 for Rhydon, and 15 for Rapidash.

Gen 3:

-With the exception of the Nido lines and Italian Jynx, you may change the Origin Game of any Ruby/Sapphire and FireRed/LeafGreen to their counterpart.
-The Colosseum gifts and XD trades all have random Natures, so you can use RNGReporter to create a valid Colo/XD PID-IV algorithm that will change them to your desire, or you can use PKHeX's built-in Mystery Gift Database to generate one.
-Channel Jirachi also have random natures and either OT gender; you can use PKHeX's Mystery Gift Database to generate one, or RNGReporter to try and find a valid PID for your specification.
-Anything in the Colosseum Unreleased folders cannot be transferred to G6+.
-The XD Elekid all are based on the Togepi trade; you can just click around the Pokemon's moveset box's border in PKHeX still in G3 format to give them the Togetic trade's moveset.

Gen 4:

-You may change the Origin Game of the Diamond/Pearl and HeartGold/SoulSilver trades to their counterpart.
-You may randomize the IVs for any of the Pokemon Ranch trades (and also the PID and Ability number of 1 and 2 for Phione and Mew only).
-The Rhyhorn can only be acquired on a Saturday in this Generation format, for those who're worried about such small details like this -- won't matter once transferred to G5+.

Gen 5:

-With the exception of Cottonee, Petilil and Basculin, you may change any of the Pokemon's Origin Game of the Black/White and Black 2/White 2 trades to their counterpart.
-The PIDs, IVs and Gender are random with the Yancy and Curtis trades.
-N's Pokemon with the exception of Zorua can be in any Ball type given it's valid.

Gen 6:

-You may change any X/Y and OR/AS trade's Origin Game to their counterpart.
-You may change the Geolocation data in the Main tab and in the Memories tab (will be irrelevant once transferred to Gen 7).
-You may change the Memory Feeling text in the notOT tab (will be irrelevant once transferred to Gen 7).
-You may randomize any PIDs and Encryption Constants.
-With the exception of Chespin, Fennekin, Froakie and Ralts, you may randomize any of the Pokemon's IVs, but you must leave the 31 IV for the specific stats of the following:

Farfetch'd = Speed
Steelix = Defense
Bisharp = Attack
Magikarp = Sp. Attack
Makuhita = Attack
Skitty = Speed
Corsola = HP and Sp. Defense

Gen 7:

-You may change any Sun/Moon and Ultra Sun/Ultra Moon trade's Origin Game to their counterpart.
-You may change the Geolocation data in the Main tab.
-You may randomize any PIDs and Encryption Constants.
-CHS and CHT languages share the same trade Pokemon; you can change any of the included CHS Pokemon's language tag to CHT.
-You may randomize any of the Pokemon's IVs, but you must leave the 31 IV for the specific stats of the following:

Machop = Attack
Bounsweet = Attack
Poliwhirl = HP
Happiny = Sp. Attack
Graveler = Defense
Steenee = Sp. Defense
Talonflame = Speed
Hawlucha = Attack
Noibat = Sp. Attack
Barboach = HP
Arbok = Defense
Trevenant = Sp. Defense
Shellos = Defense
Tauros = Speed