I’ve had this happen a couple of times
In this case I picked Mag/Cable/Sent, opponent picks Mag/Storm/Psylocke
screen says I have Storm/Cable/Sent, him Storm/Cable/Tron.
We’re fighting Magneto vs Magneto, I kill his then all of a sudden Cable comes in (who he didn’t pick) but he’s doing storms moves. Same noises, cable lightning attack etc. Then the game just freezes. Here’s a picture of it happening once, I think that’s cable doing his qcf + k move in mid air who knows.
i’ve had one happen 3 or 4 times where I’ve air thrown someone with bone claw wolverine and the clock just kept ticking but we were frozen. took the game to time over then back to menu.
also once I was playing someone who was about to do a super with doom and I did one with cable and the screen just turned black and froze
pretty sure none of these glitches are in the arcade version or any other console one