Canon champions (mandatory)
>Lance
>Steven
>Alder
>N
>Iris
>Diantha
Rivals (probably)
>Silver
>Barry
>Cheren
>Bianca
>Hugh
>The shameful trio
Famous characters (don't overhype)
>Bill
>Eusine
>Zinnia
>Looker
>Benga
>Colress
>AZ
>Frontier brains

I would be happy if i only see the champions, although there are 186 trainer classes, Red and Blue used "Pokemon Trainer" and not "Kanto Champion" or any gimmick, so the battle tree fags shall use "pokemon trainer".