Here’s me putting out “the rest of the Nicktoon characters”. Most just have tiny bios.

PIGEON PETE

-Pete was a normal pigeon mutated by the Kraang into a humanoid. He was taught to speak by Kirby O’Neil (April’s father) and delivered a message to her when he escaped. He later allies with the show’s version of the Mighty Mutanimals, now acting as a background character. He is depicted as obsessed with bread and frequently slams into plate-glass windows.

TYLER ROCKWELL

-A silly side character, Tyler Rockwell had been experimented on by the Kraang, becoming a psychic monkey. He later becomes the brains behind Slash’s side group, the Mighty Mutanimals- his genius surpasses even Donatello’s, but he has the arrogance and faux-English accent to render him unlikable about it. His abilities included Mind Control, Mind-Reading, and Telekinesis- all amplified by a helmet he constantly wore. He also has the basic powers of a fairly large monkey, making him strong, fast and agile- his mental abilities give him enough foresight to predict others’ attacks, though for every episode but his debut he’s pretty much just a jobber.

SPIDER BYTEZ (Vic)

-Spider Bytez was a name given to a one-off duo of monsters in the 2003 show’s Back to the Sewer season. They were created by a demonically-possessed April, and beaten quickly by Casey Jones & Raphael.

-In the 2012 Nick Toon, the name is given to a big, fat, annoying guy voiced by comedian Lewis Black. Looking and acting an awful lot like Carl from Aqua Teen Hunger Force, Vic was filming the Turtles and planning to get rich off the footage. However, he was abducted by the Kraang, who wanted the footage for themselves, and he ended up mutated into a hideous, rotund spider-monster with a mouth in its stomach and arms surrounding its head-body. In this, he looked an awful lot like Octo from Clayfighter 2. Even more furious over this turn of events, he absolutely wrecked three of the Turtles in a fight (this was actually when I realized that the heroes were DEFINITELY low-level, PL 8 heroes in this continuity as well, as a brand-new villain can effortlessly trash the team), but Raphael, sent home due to his temper, returned in a calmer state and carefully used his skills to defeat Vic.

-Spider Bytez only gets one more appearance for real- he is chased down and captured by the Kraang, then freed by the Turtles. As Black was a celebrity “get” of sorts, I can’t imagine the creators wanted him as a regular. The character only appears in one background scene after that- watching Mondo Gecko’s race.

-Spider Bytez is one of those one-off foes who does really well at first, but is eventually “figured out”- he easily goads Raphael into getting too aggressive and making mistakes, but is beaten once Raph becomes more level-headed.

See now you’re pandering to slavering nerds, lol. This is just freaking Raven but Japanese!

SHINIGAMI

-Shinigami is someone I’ve never heard of- she came in WAY LATE in an “I want you to meet an old friend of mine” kind of way, where she was an old friend of Karai’s from Japan, had magical powers… and was only just now showing up to help her. She aides Karai in taking over the Foot Clan. She was a Mage of sorts- she could hypnotize people, turn into a black cat, and used a kusarigama (bladed chain).