Are you talking about the wild pets on timeless island or the celestial tournament pets? If wild pets easy to catch with almost any team just have the terrible turnip or molten corgi in group since they have moves that don't kill a pet only at most takes them to 1 hp.
As for the tournament just type celestial tournament into the search here in pet battle forum and there are multiple threads with teams and strategies. My personal favorite is a you tube channel called wowpetbattles run by enfuego who posts here time to time. Very good strategies and he tries to use easy to get pets too.
Is the first guide I found when I searched and it was the only one I needed. It is very well put together. Has multiple options for pet teams in the various fights and an excellent breakdown of moves for each fight/pet combo.