Joust: It's like the running punch's big brother. Does the player have actual air control? It looks like the player's internal velocity can change while in mid-air.
Fragmentation: This may be my favorite, perhaps because the effect is elegantly simple, yet novel. It'd be cool if physics models had a flag in a shot's parameters to allow it to fragment, and if so it uses the max contrails to know how many fragments to create. Of course nobody's going to change the physics model format, but it's fun to postulate how this effect could've fit natively into the engine.
Freeze: I'm guessing you're holding the mic button to charge the freeze ray? Why didn't it affect the juggernaut? It'd be cool if you could swap the color table of the enemy on the fly so that it turns gray while frozen.
Shockwave: Ooh, now make them bounce off the walls!