Senichi

Satchel is a character of the day who appeared in You're a Star, Larvitar!.

Satchel asked Ash if he wanted to battle, and Ash accepted, saying he wanted to prepare for the Silver Conference. Satchel sent out his Magby and Ash, wanting to literally fight fire with fire, sent out his Cyndaquil. Although Cyndaquil put up a good fight, Magby ended up defeating it.

When Ash complimented Satchel on how strong it was, he said that he was trying to evolve it into a Magmar. He agreed that it was strong, but said that as a Magby, it wouldn't last half a round in the Silver Conference.

Satchel's goal was accomplished when Team Rocket attacked and stole many Trainers' Pokémon. After Larvitar helped to save them, Satchel used Magby to attack Team Rocket. After it began to get the upper hand, it evolved into Magmar and sent Team Rocket blasting off.

As Ash and Satchel parted ways, they both hoped that they would battle each other in the Silver Conference. However, that never happened, and Satchel hasn't been seen since.

(Source: Bulbapedia)