Which character do you recommend to start with? Superman? Batman?
Some more info on your background would be helpful? What characters you play in other games, etc.
The whole game is beginner-friendly, there shouldn’t be any characters you’ll struggle with. Green Lantern is the “Ryu” of this game though, he has tools like a swiss army knife and is very easy to play.
For beginner players, I suggest Batman, Superman, or Aquaman.
Any character. This game’s combo system really breaks combos apart into bite sized chunks, so there is never anything too technical that a casual player can’t learn with fifteen minutes in practice mode. Nightwing is a pretty easy character to practice juggles with. The big power characters really have the ability to push other players around.