>>40574442>Removing nat dex is step 1 to making sure the champions ace isnt a fucking charizard in the futureLet's quickly assess what Champion aces have been in the past.
Gary/Blue/Whatever (gen 1) - Kanto starter
Lance (gen 2) - Dragonite
Steven (gen 3) - Metagross
Wallace (gen 3) - Milotic
Cynthia (gen 4) - Garchomp
Alder (gen 5) - Volcarona
Iris (gen 5) - Haxorus
Diantha (gen 6) - Mega Gardevoir
Kukai (gen 7, champion equivilant) - Alola starter
Hau (gen 7, champion equivilant) - Alola starter
Leon (gen 8) - Charizard
Out of 11 champions, only 3 have an ace which didn't debut in the same generation - Lance (wherein Johto is practically Kanto 2), Diantha (where her ace uses a Mega Evolution, which is the regional gimmick and is limited to old pokemon at this point), and Leon.
Ignoring that there's really no ties to connect the amount of available Pokemon and whether the champion's ace is an old mon, if we are to look at the evidence, we can see that the moment national dex is removed, Game Freak slips back into the relatively rare "make the ace an old shillmon" routine. In other words, if there's a correlation between nat dex and a champion's ace (there isn't), it's probably that removing nat dex makes the odds of a champion's ace being an old shillmon more likely.