Greninja is a shady, manipulative ninja hitman controlled by Nidoqueen.
Greninja did not visibly appear prior to the world implosion. However, he has vast knowledge of what happened during the events. He even seems to know Glaceon personally as the hero of Unova. This knowledge further adds to his mysterious personality. He also admits to being a hitman (which he refers to as "hitmon") in his old days. Whether this was before or after the world implosion is unknown.
He had recently moved to Treasure Town (specifically, October 12th, the same day Pokemon X and Y was released) looking for a new life. This is just his cover, however. His true intentions for moving to Treasure Town involve returning the world to its "former glory" and bringing back humans. His reason for this is that he was the main Pokemon of a villainous team admin of unknown name, and wants to assist him in taking over the Pokemon world.
Not many Pokemon know Greninja personally, for he usually intimidates Pokemon solely with his looks, his serious dialect, and his tongue scarf. However, these Pokemon have reason to be scared, as Greninja is manipulative and cunning. He is even willing to betray his closest friends in order to accomplish his goals, or to simply even get a sick laugh or two. Being a ninja, he is also capable of appearing and disappearing at will, seemingly out of thin air. He is also very powerful, defeating all but one of his foes with ease. A notable trait he has is that he wraps his tongue around his face during battle, and unwraps it when the battle is finished. Realistically, he is silent with his tongue in the former state, speaking only with hand gestures.
- Water Shuriken (he uses this move the most)
- Dark Pulse
Being a newcomer, he does not have many relationships. He is off to a bad start, however, as he has already made two enemies, swearing revenge on the latter. Whether this is all according to his plan or not is unknown. It doesn't matter, however, as he will end up betraying each and every one of them
- Greninja is the first "evil" character controlled by Nidoqueen.
- Rhydon does not count as an evil character. He is just a douchebag and not truly evil.
- Greninja is the first Generation 6 character to be created after Pokemon X and Y was released.
- Greninja is the only Kalos Starter to be introduced while fully evolved. Fennekin has not evolved until recently and Sawyer was introduced as a Chespin. He is also the only Kalos Starter to be shiny.
- Coincidentially, Greninja is the one who caused him to evolve.