Hehe, I always use the sidekick tricks to defeat Devan/Tuf Boss and in some levels in coop, if the one I play with has died, I push him into a 1up $$
The Devan bug is really handy though, the Devil Devan dies with 1 blaster bullet if you finish devan with a stomp

When two people try to access the same h-pole at once, one of them might get stuck in the floor.

After a float lizard has lost its helicopter thing, but before it hits the ground, it takes many hits to kill it. And if you sidekick a ex-float lizard when it has turned into a normal lizard, you will fly up in the air as if it was still floating, not as if it was a normal lizard.

Super red gems respawn in coop. Might be intended though

Another common bug is getting stuck into horisontally v-shaped walls >

If you get hurt while grabbing a pole you can sometimes get stuck in the floor.

The blue bullet bouncers going through walls is also a bug.

Devan can sometimes jump into/through walls.

When you kill the Queen, the level will not end. Additionally, if you go back to near when she was, she will respawn and you will be forced back behind the "force field" that prevents you from getting past her - sometimes into walls. This is sad, as you otherwise could make a long level where the queen "falls down" and you can reencounter her later...

Turtle shells get can get stuck in springs.

If you fall on a vine you can sometimes fall through it, this bug is a plague if you use the jj2 medivo tileset.

Fish float in the air if they aren't in water, but if they could fly they would chase you out of the water too in water levels..

The Beeboys sometimes lag, sometimes don't appear, and sometimes stay still floating in the air. The raven stays still sometimes, too.

When you warp to a tile just below/right of a wall, you will get stuck.

If you have water in a level, after you activate the water, above-water lighting won't work.

If you enter a bonus level using any other event than bonus level signpost, after you complete the bonus level, you will go back to the bonus level event in the previous level and keep re-entering the bonus level every time you complete it.

When you freeze the robot boss, it will stay frozen. But I'm not sure if this is a bug.

Sometimes if you end a level as a frog, you won't get to the next level before you use jjnxt.

More bugs maybe coming up later if I remember this thread and if i get a new computer.