Silcoon, the Cocoon Pokémon. Silcoon is the evolved form of Wurmple. Using its thread to attach itself to a tree branch, it waits to evolve to its next stage. When it grows thirsty, it drinks the dew that collects on its string.
– Ash’s Pokedex
Silcoon, like Metapod, is based on a cocoon. And like Metapod, it can only learn Harden (though it could have learned other moves as a Wurmple), so wild Silcoons only have Harden.
Whether Wurmple evolves into Silcoon or Cascoon is based on its Personality value, which is essentially random. I remember when I tried to get a Silcoon for my Pokedex, the first 3 Wurmples I had evolved into Cascoons… at least it evolves at level 7, so it didn’t take that long.
Stat-wise, it has Defense, HP, and nothing else.