I was about to talk about how Leon having a signature Pokemon that was one of the starter types while also having him assimilate the unchosen starter into his team wasn't the best design of all, but then I realised that this might've been why Cinderace has a Protean clone.

Cinderace has Libero so that Charizard from Kanto won't be held back by a team with reduced type diversity. It all makes sense. Libero is extremely indirect Charizard shilling.