Here is Knuckles fighting upside-down in the air, alone, for your enjoyment...

Sonic the Fighters disables gravity for many moves and actions, contrary to my previous post. Here's what the game looks like with gravity ALWAYS applied to everything.

Sonic the Fighters has a routine which seemingly isn't used very much that disables gravity. Here's the routine in action when it replaces the "normal gravity" routine.

And here is the rng changed to always return 0!

Here's the same scene but with the random number generator modified to always return 1!

It's not mind blowing, but it's really interesting! The attract mode, the opening cutscene of Sonic the Fighters, uses RNG! That's right, it uses RNG to calculate the blackouts on monitor watching the Death Egg II from the lab where Tails keeps the Lunar Fox! Here's how the scene looks normally...

You can see how Honey reacts when blocking the various projectiles, and the heart projectile does not cause her to recoil.

When Fang uses the heart against Bean, it causes him damage. You can also see the heart bounces off the ground, and bounces straight into the air when blocked.

Sonic the Fighters has two unused projectile types: a flying hand, and a flying heart. The flying heart doesn't seem to affect all players equally, nor does it give recoil when using barrier against it.