Snivy, sometimes Smugleaf, is a Grass type pokemon introduced in the Generation of Racism.
Snivy looks like he's so much better than everyone else, but this is far from the truth. Snivy's facial expression is caused by the constant state of euphoria he is in. By burning his tail leaf he gets a high which helps him through the battle.
Fortunately for humanity, Snivy is weak to Flying, Poison, Ice, Bug & Fire so you can pretty much beat it with anything.
Smugleaf evolves into Servine, then sells its arms to its cousin andbecomes Serperior (the Pokemon). It loses some of its smugness when it evolves, but it gains it all back and more by becoming the "Regal" Pokemon.