A new boss: Egg Buggy.
Basically, Eggman sits in his Eggmobile attached to a frame with four small tank treads replacing the wheels. The treads have spikes on them, and getting hit by the spikes will cause you to lose your Rings. The Egg Buggy will chase after you, stopping to fire missiles. When it gets down to the last two hits, Eggman will start firing turret bullets instead of missiles for 35 tics at a time.
The boss is segmented, meaning running into the treads will hurt you, hitting the Eggmobile will cause Eggman to take damage, and you will be stopped by the frame.
Flagging the boss as "Deaf" will cause the boss to follow a NiGHTS path rather than having free motion. The Eggmobile will rotate in its holding clamps regardless of where the buggy is aimed. Each time you hit it, it will speed up for about three seconds, and it will not stop to fire at you. When there are two hits left, it will stop following the NiGHTS path and go into the Pinch Mode mentioned above.
When you hit Eggman for the last time, he will fly up and the buggy will explode sort of like the Emerald Hill boss, but the treads explode too.
Placing this boss will require 6 Things. Buggy Frame, Tread 1, Tread 2, Tread 3, Tread 4, and Buggy Eggmobile. Tagging the treads to Deaf will remove the spikes and you will be able to stand on them. The boss will autodestruct if any piece is missing.
This boss is able to climb stairs if the ratio is 3 fracunits of stair length or more to 1 fracunit of stair height. Alternate ratios like 6:2 and 9:3 work as well, but the boss won't be able to climb more than 16 fracunits per stair.
Yes, this boss is complicated, but it'd be really cool to see.