>>59033491What he means is that they turned Ash into a beginner five episodes after he was in the Sinnoh League semi-finals going head to head with a guy sporting a Darkrai and Latios (both of which he KOs, and nobody had ever KO'd his Darkrai). Several episodes later, he loses to a new Trainer who just got a Snivy while using the same Pikachu that tied with Latios. He also forgets that a Pokémon should be weakened before he attempts to catch it. He also has to look up a Koffing. He also places worse in the Unova League than he did in Sinnoh, the first time he regressed in rankings, and he lost to a guy who forgot that you were supposed to have 6 Pokémon, so he only brought 5 and Ash still lost with that handicap. Then a park ranger with a bunch of Eeveelutions wins the championship.
Ash being a beginner in the early anime was fine when he had an actual personality and the writing was entertaining. In BW, all of his edges have been sanded off so he's just Dragon Ball Super Goku Lite, but nerfed. In XY, he's the same, but they make him a bit more competitive and battle-focused and a lot more competent. He's not interesting though because he's still a fairly flat character this late in the series.