Wynaut?

[BaldWombat]

according to bulbapedia and smogon it is a pinch berry so you need to be under 25% health to use it.

This is correct, but the Pokemon does not eat the berry until the beginning of the following turn AFTER it drops below 25%.

 

[zyrefredric]

what happens when your health dropped below 25% during YOUR turn? (from recoil, life orb, poison/burn, confusion self-hit, etc). does it activate? do you still get the pinch berry's effect during your turn, skipping the opponent's?

 

[Colonel Darren]

what happens when your health dropped below 25% during YOUR turn? (from recoil, life orb, poison/burn, confusion self-hit, etc). does it activate? do you still get the pinch berry's effect during your turn, skipping the opponent's?

Custap Effect occurs at the start of a turn if your health is below a quarter. So if you drop to 25% from, say Sandstorm for a common occurance, on Turn 25, the very beginning of Turn 26 is when Custap takes effect.