Game & Watch was a series of handheld video games that started in 1980, which pretty much makes Mr. Game & Watch the father of the Game Boy and Nintendo DS. Or maybe an older sibling? Anyway...in Smash Bros., Mr. Game & Watch uses distinct retro moves to damage his foes. However, he only has two dimensions, so he's pretty easy to send flying.
Mr. Game & Watch's Oil Panic special catches shots and turns them into oil. After catching three, the bucket will be full and you'll be able to throw oil all over your enemies. Some shots, like Samus's fully powered Charge Shot, will fill the bucket in one go! Throwing the oil you get from a shot like that can KO your foes in a flash!