Even if Ash Ketchum's strength reached the Champion, Master, or even higher levels someday, and Lance, Cynthia, and the others were no longer his opponents, he could still battle those Legendary Pokemon.
If Level 2 Legendary Pokemon weren't enough, he could fight Level 1 Legendary Pokemon. If Level 1 Legendary Pokemon weren't enough, he could fight Arceus's Shadow Clone. If Arceus's Shadow Clone weren't enough, he could fight Arceus himself.
Invincibility?
In other worlds, maybe, but in the Pokemon World, you wanted to be invincible?
Did he even understand what a Multiverse-level Arceus was?!
I Want to Become a Pokemon Master: "Uh, I guess that's true."
Ash scratched his head. That did seem to be the case.
Since the opponents in the Newbie Tournament couldn't give him evenly matched battles, he could just treat it as an honorary copy and win the championship.
He could consider it making up for his regrets from the Memory Copy.
The rest of the time, he could challenge the Elite Level Trainers and Champions of each region. They probably wouldn't refuse.
Even if they could no longer put pressure on him someday, he could still challenge Legendary Pokemon.
It was still far too early to feel something like "loneliness."
Richest Man in the Lighthouse: "What the group owner said is one method, but don't you have another one?"
Richest Man in the Lighthouse: "Didn't you handle that method quite well in the Memory Copy?"
Tony Stark was somewhat surprised that Ash would have such feelings. With the way he had acted in the Memory Copy, he shouldn't have had this kind of concern at all.
I Want to Become a Pokemon Master: "Another method? I did it well in the Memory Copy?"
I Want to Become a Pokemon Master: "Did I do anything in