Buzz Bomber
Preferrably based off of this SMW Custom enemy: https://www.smwcentral.net/?p=section&a ... s&id=25975
Orbinaut (Unidasu and Uni Uni)
Both the Unidasu and Uni Uni types; The former will fling its spikes and is well known for it's prominence in Labyrinth Zone.

The latter appears in Starlight Zone, and will never shoot its spikes off.

Caterkiller

It's spiky everywhere but it's head. If you attempt to hit it on it's spikes, or get bumped by it, it'll split apart, its individual segments bouncing off in a specific direction, depending on which half of the enemy. It's bouncing AI should include low jump, high jump, as well as Jump (Sandworm AI).
It should also come with a Sandworm variant, that's fireproof.
Crabmeat

Of course, these dudes wander around, charging up, then firing two energy balls when the player is near.
(It is optional for you to also include the sonic 1 animal buddies.)
Update:
Sonic 2:

These guys crawl around, occasionally firing a bullet in a curved arc toward the player.

These stupid spiders, well, grab you, and hold on to you trying to detonate you. Button mashing will help you escape.

"SnooPING AS usual, I see" (sorry, had to get that in there). These things just move around like blue shy guys, but should be able to be set to hide in walls.

Basically they throw homing claw projectiles at the player. They can also stand on the ceiling! They should be unable to turn around, and should not be able to throw their projectiles behind themselves.

These robotic crustaceans scuttle around and launch their fist in the horizontal direction of the player.

Their hitboxes should be game accurate, for optimal frustration (BTW, for extra pain, only the fist should be spinjumpable.)