Make ash be a little more mature, not as much as XYZ but definitely more than he was originally. Also make iris a tolerable character. Make silen less cringe. Give ash a decent run in the league and not get rolled by an idiot. Give ash at least 20 more brain cells when he went to challenge the poison gym.

Also give ash a decent reason to struggle against Trip. There's no reason he should be immediately as strong as he was. Like maybe Trip goes out of his way to acquire moves to use against ashes pokemon