The Shredder has always been the Teenage Mutant Ninja Turtles' most deadly foe, but the TMNT can't fight an evil ninja every day of the week. It would get boring! So of course their rogue's gallery expanded to include mutants, aliens, demons and ... uh, a guy named Joey. Here's a baker's dozen of the TMNT's least formidable foes.
Look at this guy. Any time an alien is phallic and pink it's bad news, but Bellybomb makes it worse in that his primary offensive weapon is his bad breath. Bellybomb was banished to the planet Morbus for "extortion, armed robbery, man-eating, brain poaching, soul thievery, and impersonating a deity named Bob." Which, ha ha, Bob's a funny name but the dude stole people's souls. That's messed up.
This villain from the second live-action TMNT movie was a mutated wolf with immense strength... and the mind of a one-year-old. While most major villains would see these minions as problematic, unusable, or even just sad, Shredder of course made major plans based around them. The Turtles beat Rahzar and his equally dysfunctional cohort Tokka by giving them doughnuts laced with anti-mutagen serum, and then shooting fire extinguishers down their throats when they began burping too much. Don't ask.
3) Demoness of Yomi
At one point, Raphael and the TMNT foe-turned-friend Ninjara were in the Japanese underworld (long story) when a buxom demoness appeared. She was, of course, sexually attracted to the anthropomorphic turtle Raphael and threatened to strand both mutants in hell if Raphael wouldn't stay with her... with the obvious implication that he'd be her fuckslave, naturally. Raphael called her bluff and escaped, but still, weird.
One day, a sanitation worker slipped and fell into Shredder's garbage can. This was enough to turn him into Wyrm, a worm mutant. Now, leaving aside the fact that Shredder just throws away radioactive waste in a garbage can — or, even more insanely, than Shredder pays the city to regularly pick up his garbage — no one sober could ever possibly manage to fall into a trash can, making Wyrm's origin even more pathetic. He died when fighting the slightly less embarrassing Scumbug in the sewer, when some nearby powerlines came loose and electrocuted them both.
Alas, the Turtles were never menaced by Dave Mustaine's post-Metallica metal band. Instead, Megadeath was a group of cyborgs made up of Dead-Eye, Fist, Lynch and Waster, who somehow managed to murder seven of the TMNT's closest mutant friends in the Archie comic book series, including Mondo Gecko.
For extra fun, the Turtles apparently told Waster they'd let him live if he revealed some info about an alien invasion, which Waster gladly gave up, "But due to his involvement with the massacre of the Mutanimals, the Turtles go back on their word and kill him as well." Fun! It's also worth noting that Lynch wore a giant skull on his crotch.
I literally know only two things about Monsterex: 1) he is a fusion of Dracula, the Wolfman, the Mummy, Frankenstein's monster, and the Creature from the Black Lagoon, and 2) he is the greatest character in Western literature. He was created when Krang fired a ray at a TV showing a classic horror movie marathon (please do not think too hard about this). I need a Monsterex comic, book series, TV show, and movie franchise STAT.
7) May East
Just your average evil sorceress who wears skulls for a bra and who happens to be April O'Neil's ancestor, whom April accidentally wakes up and who then possesses Splinter, forcing the Turtles to fight their master. Now, May doesn't just possess Splinter; she actually shrinks and goes inside his brain, and the TMNT and April do the same, and they all have a silly fight in Splinter's brain. Somehow making Splinter sneeze saves the day and eventually May just leaves and no one cares.
8) Vid Vicious
Part man, part satellite dish. I... think that's all that needs be said, really.
Apparently during a certain time Raphael was being an arsehole and interfering with the Turtles' training with Master Splinter. The other three Turtles decided to get back at Raphael by putting a leech on him, like you do. For some reason, the leech sucked the mutagen out of Raphael, not blood, and became an anthropomorphic leech-man while Raphael reverted back to a regular turtle.
I bring this up mostly because the way this problem was solved is that Raphael the turtle had to bite Bloodsucker and suck his own mutagen back out of the creature. At which point the turtles returned the leech back to the river where they found it.
What, you don't know of the nefarious TMNT villain named... Joey? Well, it's probably for the best. Joey was a low-level mob thug whose truck full of... something bad was hijacked by the Turtles. As his mob boss was about to have Joe executed for losing said truck and making up a story about anthropomorphic turtles trained in ninjitsu, the TMNT burst in to kick arse, causing the mob boss to die of a heart attack and Joey to go insane.
He basically became a turtle-obsessed Punisher, with the distinction that he thought everyone he saw was a turtle. Somehow, Joey tracked the Turtles to their lair and attacked, at which point Master Splinter pulled some crazy ninja mind trick and convinced Joey he too was a turtle. Joe committed suicide. The end.
11 & 12) Kid Cortex and Oxymoron
OK, try to keep up: Christopher Columbus discovered America with his brother Louie. When Columbus went back home Louie decided to start up a farm in New York. This farm for no reason whatsoever exists in another dimension, except for one day ever century, when it appears in New York City's Times Square.
On the day in question, a smart, belligerent goat and idiotic bull escape the farm, travel to NYC's sewers, drink sewer water with mutagen in it, and become Kid Cortex and Oxymoron. They decide to turn Central Park into their own farm. The TMNT try to stop them. Kid Cortext and Oxymoron actually kick their asses, and the only reason they give up their prime NYC real estate is because Louie Columbus somehow manages to convince them to.
Whatever the Michael Bay-produced TMNT movie will do to their turtles, it won't be more ridiculous than this.
The Demoness of Yomi wasn't the only encounter the TMNT would have with Hell. In fact in the Archie comics, they're main antagonist was a gent named Mr. Null, who was arguably Satan himself. He was constantly trying to destroy the environment and had plans to sell Earth to an alien named Maligna; the more evil he did, the more demonic he began to look, with horns sprouting from his head and giant bat-wings from his back. He also controlled four demons patterned after the four horsemen of the apocalypse. Certainly, a more formidable foe than Bebop or Rocksteady. Or Joey, for that matter.