research [Gen IV] Counter, Mirror Coat and Metal Burst coupled with damage-reducing berries

[MeroMero]

Maybe this was already known but I couldn't find anything about it on the Internet, so here I go.

I think I may have found something weird about how the Counter / Mirror Coat / Metal Burst trio behaves against damage-reducing berries (including the Chilan Berry).

Note that this behavior is for Gen IV only (Gen V onwards it behaves like one would expect it to.)

What is already known:

• Counter sends back to the attacker 200% of the damage taken by a physical attack, and fails against special attacks and Ghost-type Pokémon.
  
• Mirror Coat sends back to the attacker 200% of the damage taken by a special attack, and fails against physical attacks and Dark-type Pokémon.
  
• Metal Burst sends back to the attacker 150% of the damage taken by an offensive move, provided the attacker was faster this turn.
  

What I accidentally stumbled upon:

Damage-reducing berries, when activated, doesn't touch the actual damage value (like it does with Focus Sash for example), rather it seems that the calculation for halving the damage is done separately from the actual damage value read by the game.

Hence for example if a move was supposed to deal 200 HP damage, the berry will activate and will deal instead 100 HP damage (rounded down), but the game doesn't update the damage value (it still reads it as -200).

Thus if a damage-reducing berry was activated this turn and the user happens to use one of the "Sends back to attacker" move, it will deal 200% damage (150% damage if Metal Burst) of the value stored in-game instead of the actual damage dealt.

That is in this example, Counter/Mirror Coat (Metal Burst) would deal 400 HP (300 HP) damage and not 200 HP (150 HP) like one would expect!

If this was already known, I'm sorry and you can slap me a thousand times.

[JohnTravolski]

I didn't know that, pretty neat.