In general:
- New music, more attune to the classics.
- Get rid of the stamina bar.
- Replace the forward dash with the run.
- Less frames for start and recovery animations.
- Less frames for jump ins (less floaty jumps).
- Convert frog jumps to roll jumps for some klassics chars like Raiden.
- Bring the buff hammer for some variation' exclusive moves like in Unbreakable, Hat Trick, Dualist, Spectral, etc.
- Change the block mechanic in order to allow you to start the offensive without the need to let go the block button after blocking an attack (or let you hold a button during block stun in order to let the move come out as quickly as possible after letting go the block button, somehow ala kof).
- Let you choose the direction of your roll after hitting the ground.
- Make the block breaker a pushblock ala IGAU that cost you 5% health and 1 meter bar.
- Make the overheads more "reactable" (slower than mid or high starters, always).
- Adjust the auto-correct function for jump ins during cross ups.
- Give 60 (maybe 90) real seconds to the timer.
- KP2 should include 4 klassic stages plus Noob-smoke (as 1 char), Cyrax-Sektor (as 1 char), Havik, Reiko, Skarlet and...
... Rain
(or Shang Tsun).
That would do. Anyway I would still play it without the changes.