Ketxki

Hello there my fellow trainers, so this is my first time really getting into the nitty gritty of pokemon stats and that nature so i would like to ask is it a requirement to have a 6x31 or a 5x31 team when getting into PvP, re-battling gym leaders, Tournaments as of the moment i am pretty clueless when it comes to this sort of stuff since i only really played main story in past games and didn't really cared about PvP at all, so any information about this stuff will be greatly appreciated!