Chansey

Imposter Chansey is the single most defining set in BH. With astronomical HP that is preserved after transforming compounded with a potential Eviolite boost, it can turn into a significantly bulkier version of the foe, making it a blanket check to most offensive Pokemon. Defensive Pokemon are not safe either, as without proper teambuilding, Imposter users can take advantage of their enormous bulk to become incredibly difficult to punish, allowing them to utilize the constant PP Imposter can provide to stall out the foes. As a result of these traits, every team must Imposter-proof: be well prepared for and carry responses to all of its own Pokemon. Imposter also provides invaluable scouting information in a tier where anything is possible to allow the player to make more informed decisions. Additionally, Imposter Chansey and Blissey provide role compression by Imposter-proofing some special attackers when not transformed. However, every competent team will prepare carefully for Imposter, limiting its effectiveness; examples of common generally Imposter-resilient sets include Plate + Judgment users like Arceus-Ghost and Thunder Cage + Strength Sap users like Arceus-Electric. Imposter users also dislike the metagame having an abundance of offensive Pokemon such as Eternatus and Mega Garchomp that are weak to their own STAB moves, reducing their defensive utility and making them more difficult to fit on teams.

Alternatively, non-Imposter Chansey utilizes its astronomical special bulk and respectable physical bulk with Eviolite to serve as a strong special wall capable of answering threats like Eternatus and Take Heart Arceus formes. It differentiates itself from Blissey through the extra bulk from said item allowing it to sponge certain physical coverage moves like Eternatus's Shell Side Arm much more comfortably. Its exceptional special bulk also lets it forgo Ice Scales in favor of Magic Guard, allowing it to be very resilient against residual damage from entry hazards, Thunder Cage, and status conditions. Chansey's minuscule Attack also lets it neutralize Strength Sap healing from the special attackers it aims to wall to support its offensive teammates. However, Chansey is rather passive, causing it to be a momentum drain against Pokemon such as RegenVest users with Knock Off and Flutter Mane, which an issue amplified by its lack of passive recovery from Leftovers, forcing it to spend turns healing more. It also has a minor opportunity cost of not being able to use Eviolite + Imposter.