Chansey

Chansey boasts a gigantic base 250 HP stat that, when coupled with Eviolite, allows it to be a very bulky Pokemon that serves as a powerful special wall. Imposter allows Chansey to copy the opposing Pokemon's typing, moves, and stats minus HP, while retaining its greatest assets in its huge HP stat and Eviolite boosts, allowing it to act as an all-purpose check to almost any Pokemon, as it will always be bulkier. Imposter also inherits the opposing Pokemon's stat changes and, when coupled with its preserved bulk, allows Chansey to be a formidable check to nearly every setup sweeper in the metagame. Therefore, Imposter Chansey puts a huge strain on teambuilding, as teams must carry checks to their own Pokemon to avoid losing multiple Pokemon or, in more extreme cases, the game entirely to a Transformed Chansey. Additionally, this ability allows Chansey to effortlessly scout for the foe's moveset simply by switching in, an extremely valuable asset to have in a metagame where movesets can be unpredictable. Alternatively, Fur Coat propels Chansey's middling Defense stat up to a respectable amount, allowing it to act as a sturdy mixed wall that is able to switch into many powerful Pokemon, like Mega Diancie and Kyurem-B.

However, due to how omnipresent Imposter Chansey is, every competent team prepares thoroughly for it, reducing its overall effectiveness. A few offensive Pokemon, such as Judgment + Spooky Plate Mega Gengar and Poison Heal Regigigas, are capable of defeating an Imposter Chansey one-on-one by exploiting certain things Imposter is unable to copy, such as the opponent's item and status condition. Additionally, Chansey's item choices are quite limited, in that it often requires Eviolite or Choice Scarf to be a huge threat, making it quite weak to Knock Off. This means that unlike other bulky Pokemon, Chansey cannot afford the luxury of choosing an alternative item such as Safety Goggles, Leftovers, or even a Z-Crystal for more flexibility, making it quite predictable in that aspect. Therefore, Chansey's non-Imposter sets are vulnerable to moves like Taunt and the ever-so-common Spore thanks to its limited item selection.