How would you change any of the champion's teams? I looked at all of them and this is how many new pokemon each champion had based on their region

Blue - 6
Lance - 0
Steven - 6
Wallace - 4
Cynthia - 5
Alder - 6
Iris - 4
Diantha - 5
Prof. Kukui - 3 (Including Alolan Ninetales)
Hau - 3 (Including Alolan Raichu)
Leon - 2 or 3 (If you choose scorbunny he gets a Mr. Rime)

I think Leon could use another galar pokemon, but it can't be any of the gym leaders aces so I'd go with either Grapploct or Boltund.