Rosalina is a skilled fighter, but she won’t be able to match up against Greninja. Greninja has a lot of attacks up his sleeve and he’s a force to be reckoned with. His speed will enable him to dodge Rosalina’s attacks and his defensive abilities will enable him to stay in the game for a while. No matter how you look at it, this is a dangerous fight for both combatants. Greninja wins.