>>57091150>The fact that Ash has been frozen as a character is another reason why it'd be very difficult to do a post-Championship arc- which is probably why he had to leaveEven during MPM , Ash had more character than the entire cast of Pokemon Horizon. His only actual flaw was his current interaction with people which wasn't as fun as OS Ash however that's a problem that every character has in current pokemon anime and not just Ash's problem.
In fact, the entire cast of Horizon has been frozen as a character since the start of Horizon. Liko still has no actual goal yet and Roy just wants Black Rayquaza because the plot says so.
People believed that old Ash has returned on MPM episode 02, why? Because Ash and Misty interacted the same way as they did in the original series, not because Ash revert back to old Ash. At the end the answer is right front of us, Ash just needs to interact with people the same way original Ash did.