Ghepardo

Hello. Im trying to beat Radomus but this battle is almost impossible for my actual team. I searched yt and I see, that many people have more high-level(60 in this case) pokemons in their box. I don't know if they really grind so much, is there any way to quickly train pokemon needed for some fights at this point in the game or I must grind a lot of time to get needed pokemon on enough levels? Thanks in advance for reply