>>360355151) He doesn't know how to teambuild. Ash just picks whatever Pokemon he feels like to battle certain trainers, usually the Pokemon that he caught in a journey. Ash rarely selects Pokemon based on type advantages.
2) Ash's Pokemon have suboptimal movesets. Pikachu knows Thunderbolt, Electroweb, Iron Tail, and Quick Attack; this combination doesn't offer the best type coverage. For example, Pikachu lost to Iris's Excadrill because the latter resists or is immune to all of Pikachu's moves (Electro Ball was there instead of Electroweb, but the point stands). Many of his Pokemon have 2-3 moves of the same type and then a basic Normal-type move. He doesn't factor stats into account either; Pokemon such as Noivern and Torterra use moves that are calculated from their lower offensive stat.
3) Ash hardly evolves his Pokemon. Ash knew from the beginning that Pokemon get stronger when they evolve, yet he only evolves about half of them. XY is the only series in which Ash has a near fully-evolved team, aside from Pikachu.
4) Ash hardly trains his Pokemon. Many of his Pokemon learn moves and techniques on their own. His strongest Pokemon, namely Greninja and Charizard, have gotten stronger completely on their own without any direct input from Ash.
5) The most important: Ash forgets everything he learns in the subsequent series. Ash was introduced to various training methods such as becoming attune to nature to improve one's reflexes and senses, observing the battlefield or Pokemon to determine the next move, turning the opponent's Pokemon's power against them, etc. Yet Ash doesn't incorporate these training methods into his own battle style. Ash still uses the reckless, straightforward battle style that is hardly effective.
