HELP ME WITH WHICH IS THE BEST TEAM FOR CAMPAIGN

Xtreme X-men are great but they aren't easy to get and for 7-2 you need city characters and they won't work.

There are better city characters than what I'll mention but mine should work and be decently ez to get, they won't have much long term value right now so you'd only want to build them to like gear 11-13. Somewhere in that range.

Squirrel Girl, Shang-Chi, Ms Marvel would be my top picks. Then maybe JJ and Spiderman. That's assuming you need to unlock characters.

If you happen to have unlocked Peter B. Parker, Peni Parker, Pavitr, Spiderman Noir, and/or Ghost Spider they are better/have more value and should work. Peter B. and Peni in particular could probably carry nearly any hero spiderverse thru the campaign.

Gwenom, Ghost Rider (Robbie), Cloak, and Dagger are also decent. The first 2 in particular are pretty good value.

I agree with Sinister 6 being the best villain team if you can get Doc Ock and at least 1 other Superior 6 since then vulture can give your whole team drain which should be enough sustain when paired with Ock. Lizard or Kraven are ideal if you can't unlock Green Goblin (Classic).

Best heroes go for xtreme xmen, villains do sinister/superior 6. Nexus I’m pretty sure you can use any

S6 for villains (my favourite combo is Lizard, Vulture, Doc Ock, GGc, Mysterio. If you don't have GGc, use Kraven.)

For heroes I recommend Xtreme Xmen, as they are good in everywhere. Other good hero teams are Pegasus, Out Of Time and Spider Society.

For Nexus there are different requirements in each level I think.

If you know which toons are new and which ones are old, go for the newest toons, they have longer lifespan and are more worthy investment in general.