Let me take a step back though in case the songs lyrics are a tad confusing – Teenage Mutant Ninja Turtles focuses on four turtles who wandered into some ooze that made them far larger than the average turtle. They were then cared for by Splinter, a human who turned into a rat because of the same ooze. Splinter taught the turtles to be ninjas, and now they fight Shredder who is actually the same guy who cost Splinter his job at a dojo (life is funny like that). Helping Shredder out on the side of evil are Rocksteady and Bebop (other mutations) and everyone's evil boss, Krang, an evil brain-like blob from Dimension X. Later, you'll meet a guy named Lord Dregg, but he's no Shredder nor Krang.
I know I've lost you already, but just stop for a second and breathe. It is pretty simple really – the Turtles fight a guy named Shredder who wears a metal mask and helmet (like Cobra Commander). Plus, the Turtles like pizza, lots and lots of pizza (see, everyone likes pizza, that makes the mutant ninja turtles relatable).
Most plots revolve around Shredder and Krang's desire to beat the Turtles, take over the world, and maybe even grab a few other dimensions while they're at it. The turtles joke around, come up with a solution, and eat pizza to celebrate after they win. The journey though tends to be a fun one and the jokes amusing. Plus, when the show concentrates on overarching season-long plots (season one being the perfect example of this), it has more direction and purpose, which may be one of the reasons the first season (which, to be fair, is only five episodes) works so well.
Teenage Mutant Ninja Turtles has already been released on DVD in individual sets/seasons (they altered how they were doing it part way through). If you have that complete set, bought in pieces, I urge you in the strongest terms not to get this one. While the discs themselves may look slightly different here, the content on each one is the exact same as what came before (even if that means having episodes there twice… as season one does due to its inclusion of "bonus episodes" from later in the show's run). No attempt has been made to standardize the menus which actually change from being 4:3 to 16:9 part way through, and it doesn't look as though anything has been to clean the images either. There are also some episodes that are kind of out of order.