A bustable FOF type that only breaks when using the "drill" action in NiGHTS mode.
Also, some obstacles (Rocks would be the best idea for this, though, spike balls that hurt you when colliding with them might work) that are destroyed when a paraloop is performed around them would be nice.
And a Twin Seeds-style setup. Where the player has to jump off a cliff into a bottomless sector, where the drone is activated. Would probably only require a sector type and a special drone (maybe not even that?) to recreate. It'd be as simple as placing the drone exactly where you want it to start, and it sends the player there upon contact with the sector. Would have to have the drone "push" up, almost as if it hit a bumper, though.
I would like to see the palette be something the user can change. And, speaking of palette changes, a new set of not-gray greens would be lovely.