Blissey, the Happiness Pokémon. It is kindhearted and loves helping people. Blissey is the evolved form of Chansey.
– Ash’s Pokedex
Blissey has the highest possible base stat in its HP, 255. It also gives the most amount of EXP(See my max exp gain experiment). It also has very high Sp Defense (the highest of all Normal types), making it an excellent Sp Def tank. Its Defense is pretty poor though, so if you want to defeat a Blissey, use a physical move.