I can't say on the PS4. I played many years ago on the PC and you got better stuff if you played as a group and it got harder. I was also harder in the "real game". I think BETA is easy so you can progress. I played as Rocket Racoon and dead Pool a lot.
They kinda follow classes. Tank, Range, melee, magic and skill.
I played as Thing, Hulk, rocket raccoon, jean grey, dead pool.
Rocket was the most fun for me but quite OP at the time. His shield gen and groot made it easy to solo just about every boss.
I played as hulk on the beta and found the UI a bit clunky compared to the PC