Super Smash Bros. Lore!

This is not official, it's some weird stuff made up by me and my friends

Greninja

Greninja is Kirby's spy and explorer. Among other things, he has kidnapped both Ken and Wario. Originally, he was just a normal pet frog, but his owner Ness accidentally gave him sentience and ninja skills. When Kirby heard about this, he visited Ness to ask for his services. Ness didn't agree to join Kirby, but he did sell Greninja to him, because he didn't have much money and the rent was due next week.