For the person in the top left: Character #1 is Mantis, hence the Mantis ears, color scheme, and grass skirt (something that is very consistent in her comic design), Character #2 is Flash, hence the flash emblem, lightning ear covers, and lightning-bolt gloves and boots. Character #3 is mystique, hence basically everything else (hair color, skin color, dual pistols, etc.). For the person in the bottom right: Character #1 is Baby Groot (the baby part is necessary because otherwise he would be a huge hulking monster [and also not rude enough to make the middle claw joke work]), as evidenced by the Baby Groot head & Baby Groot-esque body style. Character #2 is Batgirl, hence the color scheme and costume design (except around his head). Character #3 is Wolverine, hence the claws, headgear, and X symbol on the belt.