Everyone will have their opinion on this and mines would be:
1. In tournament mode only, there are no variations. Every character has a complete set of moves. Tweak weak special attacks.
2. Fatal Blow requires 20% or less health to activate. Has no armor, has range no further than round-start, has long recovery on block and whiff. It goes away completely if used no matter the outcome. Damage scales based on the difference between each player's health (so if the FBer catches up on the opponent's health, it won't be a go-to option all the time). The 20% health requirement makes it less seen by the opponent possibly doing moves/combos that kill before the active state.
3. Chip damage can only come from special moves. Damage-overtime moves. can only place a player at 1% health. They can never kill on their own. Each bar of Last Breath takes 5 special attack hits to deplete.
4. Breakaway places the person using it at -15.
5. Remove most of the wakeup options and and leave only:
- long delay
- roll (rolls futher away from opponent)
- invincible wakeup
6. Very fast attacks (like D1) should have no + frames and slower, more risky attacks should have better frame advantage.
7. Remove all option-selects.
8. More combo routes/launchers.
9. Correct hit/hurtbox inconsistency issues.
10. Teleport moves should have slower start-up.
11. Meter doesn't regenerate during non-fighting sequences.
12. General meter gain is a little bit slower.
Then, I'd add what TrueUnderDawgGaming has suggested: