2 N's Zoroark ex - 185 Special Illustration Rare - $145.51 N has a bit of a complicated history in the Pokemon games, especially considering his special abilities to talk to Pokemon of all types and his figurehead status as the leader of Team Plasma
Some corrupted abilities are activated abilities that can be activated only if an opponent has three or more poison counters
I havent experienced that, but I know, for example, Brendon Bigley has
Able to deal with virtually any problem, Capsize couldn't be dealt with through conventional means (you'd usually have to kill your own creature to have a chance of fizzling Capsize)
But its existence speaks to the extraordinary power of the Pikachu brand: the most valuable Pokemon card ever made features the most famous Pokemon ever created, and that feels exactly right
therefore, three may be the only count necessary, and four is overkill