I'll be a challenger.
Imo you should see how many people would actually make challenges and if there aren't enough, reduce the numbers of gym leaders / elite four members so you actually have some.
You may not use a Pok?mon carrying the following attributes:
Moves
All moves that increase Evasion only (e.g. Minimize)
All instant OHKO moves (e.g. Horn Drill)
Abilities
Inconsistent
Species
Arceus
Darkrai
Deoxys-A
Deoxys
Dialga
Giratina
Giratina-O
Groudon
Ho-Oh
Kyogre
Lugia
Manaphy
Mewtwo...