Teddy

Teddy is a young man from Ellay. He is the leader of the Bla-Bla Gang, which is responsible for many crimes in the city. He first meets Ninten in the live house after the musical performance, and challenges him to a fist fight because Ninten beat up some of his gang members. After a few turns, Teddy stops fighting and deems Ninten a strong person and asks to travel with him for a while. Teddy wanted to go to Mt. Itoi to avenge his parents that were killed there, and takes Ninten and Ana up the mountain, taking Lloyd's place.

While going up Mt. Itoi, the trio rest at a cabin on the mountain plateau. However, during their stay, they are attacked by a massive robot. Teddy got severe injuries after the ambush, while Ninten and Ana make it out safely, due to a lucky save by Lloyd and his borrowed tank. He is left to recover at a healer's house near Mt. Itoi's base for the rest of the game.

After the game's events, Teddy is shown to have recovered from his injuries and has given up being the leader of the local gang, instead choosing to become a singer. In the original Japanese version of Mother, however, it's implied that he dies. However, Mother 1+2, released in Japan, added the ending sequence that was added to EarthBound Zero, that version of the events surrounding Teddy after the game was officially added to the Japanese version of the storyline.

In-game description
Maybe he's not really rotten to the core....