Along the way Liam trained his pokemon. Wurmple evolved during this training into Silcoon. 

"[i]Silcoon, the cocoon Pokemon and an evolved form of Wurmple. It wraps silk around the branches of a tree. It drinks rainwater on its silk while awaiting evolution. Its hard cocoon repels attacks.[/i]"

Liam had also fought multiple Pidgey as well as to occasional Geodude or Ratatta.

"[i]Pidgey, the Tiny Bird Pokemon. A common sight in forests and woods. It flaps its wings at ground level to kick up blinding sand.[/i]"