Bowser

Bowser is the King of the Koopas. Mario's archenemy, but in the saga, Bowser is good. He's the more powerful on the group.

Bowser in The Secret of the Lightsabers
Is fighting Mario and Luigi, and it's absorbed by an Wirldwind.

On Springfield, he fights Marge, Lisa and Maggie, and defeats they.

On the Center of the World, when Mario units all the groups, he can fight the 8 Monsters to get the Final Boss Key and fight again Dark Bowser.

He can with the secret characters.

Bowser on Let'sa go to Brazil!
We don't know if he appears on this game.