Ash's team would be filled with Pokemon that fit his personal aesthetic ... He's done it before with Pokémon like Treecko ...
Ash's Grass-type Pokémon tend to stick with the starter Pokémon of the region he's traveling through, as seen with Bulbasaur, ...
Pikachu has a battle win rate of 89% in 538 battles, proving to be Ash's strongest Pokemon. Greninja showcases a win rate of 87% in 55 battles, transforming into Ash-Greninja to secure victories.