>>47022843Do not use your starter, Dynamax, items, and always rotate your team. For gyms, you want to use Pokémon with type disadvantages against the leader.
Also, use a level cap. If a Pokémon exceeds that cap, bench it until you reach a certain point.
Beginning to Wild Area - Level 10
Gym 1 - Level 20
Gym 2 - Level 24
Gym 3 - Level 28
Gym 4 - Level 32
Gym 5 - Level 36
Gym 6 - Level 40
Gym 7 - Level 44
Gym 8 - Level 48
Semifinals - Level 49
Macro Cosmos - Level 51
Finals - Level 53
Rose - Level 55
Leon - Level 60