DP ash is the best for me. I can't forgive XY Ash for releasing Greninja and Goodra. DP ash never pulled that off. Gliscor return to Ash later on so that was okay.
I consider them released. Owning their pokeballs means nothing if they are stuck in a region that is not Kanto where they can be at oak's lab.He had a good reason to keep Greninja and Goodra in Kalos and he never released them he still has their pokeballs.
OS Kanto Ash had the best personality, but was the worst in battling. DP Ash is the best at battling cause he was smart enough to pull old Pokemon to fight in the league and tried new strategies.
Well I think the reason I don't like Ash using his old pokemon is because not only because they have the chance to get nerfed, but because his old pokemon has their time to shine and now its the newcomers turn.
Not that much though.
This is well explained in DP when Dawn tells hIm to ask Oak for any of his Pokemon from other regions so he can beat Roark without problem but Ash says he wants to get stronger with his current team and overcome whatever it takes to reach his goal. This was in-character for Ash so we can assume Ash doesn't want to take the easy path. He prefers to start over and get better by struggling and overcoming hardships.
DP Ash is not the best and he will never be. OS Ash is the best because he gotten stronger in Kanto and Johto, he learn a lot in those two regions and he didn't get reset in them either.
XY Ash is good as an Pokemon trainer, he would beat DP Ash in battle.