Good news - you can play 4 characters, bad news, it's not easy lol.
2 normal - Mitsu and Tira. You can get to Kilik and Zasalamel as well though.
Unlocking ='s go to single mode / create your own character / fly through - just make a character and approve it for battle, then as it gets past the 'face off screen' have the opposite controller hit start.
You'll have Zal on the 1p, Tira on the second. Hit r1/l1 to 'change costume' and you'll get Kilik!@#
YOU CANNOT SWITCH BACK HOWEVER. Also, it's set to time and 3 out of 5, then totally restarts back to the demo screen. Solution - play 2 out of three and restart, or just stop before someone dies.
Anyway - now you know, and can pit those three against each other, or from the normal screen Mitsu / Mitsu or Tira / Tira or of course, Mitsu Tira.
Also from good sources I've been told that this isn't a full demo / there are more moves - but yea, if you want to get into it quicker, have 10$, or just want to start with that sytem now - here ya go.
Anyway, it's what I know / have been told at least. Zal - your not seeming too bad. Kilik - you might be? GASP - FEASIBLE?! Oh, blessed be the potential.
x posted to the 2 sc communities I know.