Ash's adventure in the Pokémon anime is one of the longest-running stories in the medium's history, running for 1232 episodes over 26 years. Over that impressive amount of time, Ash has encountered many Pokémon, many of whom he has added to his battling team. And, because Ash tends to switch out Pokémon whenever he arrives in a new region, his team has contained many different combinations of Pokémon.
Source：https://www.cbr.com/strongest-pokemon-ash-never-caught/
