Chansey

Even in a fast-paced metagame such as Battle Spot, where offensive Pokemon are heavily favored over defensive ones, Chansey still stands out as one of the best walls in the game. With stellar HP and Special Defense, Chansey is able to sponge hits and then force out powerful special attackers such as Thundurus and Volcarona. Chansey's lack of Defense is somewhat alleviated by the use of Eviolite, further improving her tanking capabilities and allowing her to beat mixed attackers such as Greninja. Chansey has access to a variety of support options that let her assist her team, such as Thunder Wave to spread status onto the opposing team, and Chansey can absorb incoming status as well thanks to Natural Cure. Unfortunately, Chansey's passive nature leaves her vulnerable to Taunt users, and with only base 35 Special Attack, Chansey cannot properly make use of coverage moves, meaning that most Ghost-types are able to completely wall her. As Chansey is outclassed by Blissey without Eviolite, she is very vulnerable to moves like Knock Off and Trick, which will severely cripple her ability to sponge hits. Mega Gengar can take advantage of this and trap Chansey, knowing that she will almost never hold Leftovers or Shed Shell over Eviolite.