So, I assume you're talking about in-game teams. Since you know...no MegaEvos in official tournaments.
Mkang is still really good, even after the nerf. Fake Out, Sucker Punch, and Low Kick are excellent moves.
You don't have to run any one set on Aegislash. That thing is one of the most versatile pokemon ever made.
Toxapex is the best tank and the worst teammate. I find his middling offensive stats to be too underwhelming to be useful on the cart. But that's a personal preference.
You know, it'd be a lot easier to give you help if we knew WHAT you were doing. Just saying "Help me use these 4 pokemanz" doesn't tell us anything.
You'll usually wind up getting vague, or wrong info. Or just "Git gud".