>>52026508He was already E4-level in the Battle Frontier and then he was treated as equal to Alain who was superior to an E4 and could qualify for the Masters 8. SM had him undergo a training arc with Pikachu using Tapu Koko as their overarching rival and Professor Kukui once defeated the Kanto E4 and reached Lance, when Lance was the second strongest trainer in the previous PWC. Ash defeated Kukui even with Kukui getting Tapu Koko as help.
With all that in mind, is it really so strange that he would be stronger than any E4 by the start of JN? Him defeating E4s over the PWC is just normal. He was able to closely match Steven and Cynthia in their battles when limited to one gimmick and edged out a win against both, which is a reasonable power leap from already being tougher than any E4.
Then with Leon, Ash was given permission to go all out and use every single gimmick he had access to. So Ash with no restrictions could surpass Leon but with restrictions would lose to him, just as Cynthia or Steven would.
So in short, restricted Ash is as strong or stronger than Cynthia and Steven. Ash without restrictions is as strong or stronger than Leon.
