yesterday, I completely forgot to mention the other new character introduced during season two who would become a member of the Turtles' family.
It is, by far, the weirdest mutant in any iteration of the Teenage Mutant Ninja Turtles, which, considering some of the character introduced over the decades, is a pretty bold statement, I realize. I am, of course, referring to Ice Cream Kitty.
Ice Cream Kitty was once an ordinary stray cat, lurking around the background of various episodes until season two's episode "Of Rats and Men," in which The Rat King returns and attempts to take over the city with an army of giant rats. In one scene, April brings the stray cat to the Turltes' lair, and asks Michelangelo to watch it for a moment. I was fairly certain it was going to end up being the cartoon version of Klunk...until it licks some spilled ice cream of Michelangelo's, and then some mutagen and began to grotesquely disintegrate (Mutagen must be delicious, based on how often it gets licked by animals in this show). Luckily for the cat, falling apart was just part of its mutation, and it then transformed into, um, Ice Cream Kitty—a cat made of ice cream.
It became Mikey's pet, and he stored it in the Turtles' freezer, where it would generally cameo whenever someone needed to get something out of the freezer. When the Turtles flee the city at the end of the season, Ice Cream Kitty comes along—in a cooler.
The above image is actually from season three, during a scene in "Buried Secrets" where Michaelangelo opens up to it while making a cherry-topped whip cream turban for Ice Cream Kitty.
Kevin Eastman apparently voiced Ice Cream Kitty (whose dialogue is limited to "meow"), although I noticed he didn't get a voice credit during any of the episodes in season three. If he did continue voicing Ice Cream Kitty after the mutant's first appearance, Eastman does a pretty good cat impression, as Ice Cream Kitty would hiss, yowl and make various other cat noises beyond the standard meow in season three.