In pokemon go pvp the best pokemons are :
great league: 0 attack, 15 hp, 15 defense – closest to 1500 cp.
ultra league: 0 attack, 15 hp, 15 defense – closest to 2500 cp.
in those league since you have upper cp range, the best pokemons are those with 0 attack so they will be in higher level and can give more charge attack in the same time.
in master league you need 100iv pokemon since you don’t have cp limit.
you can search pokemons by 0 Attack 15 hp and 15 defense in pokemon go.
search those pokemons for pvp (and make sure they close to 1500 or 2500)
for master league search this : 4*
and get all 100iv pokemons