Use a team with the indicated characters to get the indicated bonus:

Age of Apocalypse (Any four heroes with Age of Apocalypse skins): +100% attack rating
Agile Warriors (Nightcrawler, Sunfire, Toad, Deadpool): +5% experience points
Brotherhood of Evil (Juggernaut, Magneto, Scarlet Witch, Toad): +5% experience points
Bruiser Brigade (Juggernaut, Colossus, Wolverine, Rogue): 20 energy gained per knockout
Dark Past (Rogue, Deadpool, Gambnit, Wolverine): 5% damage inflicted goes to health
Double Date (Rogue, Gambit, Jean Grey Cyclops): 20 health gained per knockout
Energy Corps (Gambit, Bishop, Cyclops, Iron Man): +5% damage
Family Affair (Magneto, Professor X, Scarlet Witch, Juggernaut): +5 health regeneration
Femme Fatale (Storm, Scarlet Witch, Rogue, Jean Grey): 5% damage inflicted goes to health
Forces of Nature (Storm, Iceman, Sunfire, Magneto): +10 to all resistances
Heavy Metal (Colossus, Juggernaut, Iron Man, Magneto): +10 to all stats
New Avengers (Iron Man, Scarlet Witch, Wolverine, Bishop): +15% maximum health
New X-Men (Nightclawler, Storm, Colossus, Wolverine, Sunfire, Bishop): +15% maximim health
Old School (Cyclops, Jean Grey, Iceman, Magneto, Toad, Professor X): +15% max energy
Raven Knights (Iceman, Professor X, Iron Man, Deadpool): +60% techbit drops
Special Ops (Bishop, Deadpool, Nightcrawler, Gambit): +5% damage