If I use Drapion VSTAR's "Hazard Star" VSTAR Ability to poison my opponent's Pokemon with 3 damage counters during Pokemon Checkup, and I have Radiant Hisuian Sneasler with the "Poison Peak" Ability in play, does my opponent put 3 or 5 damage counters on their poisoned Pokemon during checkup?
Five damage counters. Poison Peak adds 2 damage counters to whatever the current number of damage counters are being placed for poison.
Source: Lost Origin FAQ; TPCi Rules Team (2022-09-08)