Mr. Game and Watch
From Yb Timeline
History
One day Mr. Game and Watch took a wrong turn and somehow ended up at the YB HQ. Being completely lost, he decided to join the group. Early on he showed his common sense when he destroyed an assassin robot by throwing water on it. He was around when the gate to the Shadow Dimension was opened, leading to the Shadow King's invasion of Star World. Unfortunately he fell asleep while they were at Twilight Town and was blasted by a missile, injuring him. Koop and Jade brought him back to the HQ and he was healed by the newly-arrived Dr. Mario.
Around this time Phazon began to appear on Star World, mutating some creatures. Koop detected one such creature lurking about at Yoshi's Island, and so they went there to fight it with some prototype weapons he had made. Mr. Game and Watch was knocked out before they went out, though, and was dragged out by Chibi with no weapons or protection. The creature turned out to be a monstrous, mutated shy guy. A meteorite made of phazon fell out of the sky and hit the shy guy, mutating it further and increasing its size to thirty feet tall. Somehow Mr. Game and Watch fell asleep during the fight. When next he woke, they had incapacitated the shy guy.
Mr. Game and Watch was one of the YBs who went to a party hosted by Princess Peach in honor of them. Unfortunately, the party was interrupted by Metal Top, who used a speech Peach gave to awaken the Beanstar. It then raised Peach's Castle into the sky with a giant version of itself and used the Beanstar to become invincible and blast the YB out of the castle. To defeat Metal Top, the YBs traveled to Star Haven to get the Star Rod, but found it had been shattered. This sent them on a journey to rebuild it from the shattered fragments, during which Mr. Game and Watch was turned into a dancing banana temporarily.