ITT: we buff pre-existing abilities. I'll start.

>Big Pecks
Original effect: defense can't be lowered.
Buffed effect: Increases defense by 50%; defense can't be lowered.

>Color Change
Original effect: changes typing to match that of the last move it was hit by.
Buffed effect: changes typing to match that of an incoming attack.

>Defeatist
Original effect: halves attack and special attack when HP is under 50% of its max.
Buffed effect: halves attack and special attack when HP is under 1/3rd of its max.