>>57342312Dumbfuck, the way things are set up are to let Ash get "redemptions" for his most notorious league losses.
Steven's just an appetizer but nonetheless represents a redemption for his loss in Hoenn to Tyson. Fittingly this time around, Ash is the trainer with incredibly powerful Pokemon and an iconic not-fully-evolved ace.
Cynthia is Ash's redemption for his loss in Sinnoh, and by beating Cynthia, he's basically able to beat Tobias in spirit, because Tobias never became champion despite earning the right to challenge the Sinnoh E4 + Cynthia.
Leon is something of a package deal as his placement is built on the the losses of Lance and Diantha, but most notably he represents the ultimate redemption, the Kalos League, based on the fact he mogged Alain. By beating Leon, a trainer whose ace is an extremely powerful Charizard who transforms, Ash proves he can defeat Alain in spirit by beating a trainer who is effectively an even stronger version of Alain, and ultimately he has no need to fight Alain because that would make for two Charizard-using trainers in the Master's Eight that Ash would have to fight, which would get dull even if they use different forms.