There's a lot of ways to say screw it, and not care about what makes animation technologically pretty. You can make character outlines really sketchy, you can eschew in-betweens for your key poses, you could literally just shift your characters across the screen. Cromartie High School goes the latter route somewhat, letting its extremities lift any concerns about its low-budget feel. It's a classic TV animation principle: you're not watching Space Ghost Coast to Coast for good animation, but because the writing and situations are batshit and hilarious. If we're going way back, you're not watching Danger Mouse, Rocky and Bullwinkle, or Roger Ramjet for anything visually impressive. Let your prejudices against "bad animation" go for this one, or else you're just gonna look like a damn fool.
Characters are scaled bigger and/or smaller as they speak, still shots are repeated if needed, character designs are copy-pasted, random background elements will pop out of bare nowhere, stock images are used in place of drawings on more than one occasion. And all this does is add to the joke. Cromartie High School is a parody of delinquent anime that takes every opportunity to be as silly as humanly possible. There are no teachers because who cares? Any acts of delinquency are largely ignored, unless they need to make a joke about, for example, Takenouchi's extreme motion sickness. It's wonderful. I love it.
Freddie Mercury is there just because. There's a soda can-looking robot that they do anything EXCEPT take good care of. The leader of an opposing school is actually just intensely into comedy. There's entire episodes about a satirical take on cutesy mascot anime that have little to do with the main cast. The gorilla gets an entire episode about working at a sushi shop based on a singular gag in the previous episode, and none of the established characters besides Mechizawa's little brother do so much as show up.
It's a seriously funny anime that echoes several low-budget peers of the 20th century. It's somewhat of a shame Adult Swim never got its hands on it, because really, this is exactly the type of show that Cartoon Network airs at 11 pm. It's short, has barely any smooth or flashy animation to speak of, and lets the clever writing and characters do the work for it. Well, I say clever, but standout jokes can range from genuinely smartly written ("We need a sumo wrestler on car two") to "our robot is now a bike, we are spending the whole episode with our main character doing cool things on the robot bike". I must add that said episode decides to have a clip show towards the end, and none of the clips have much relation to each other in the first place. If you really care about that sort of thing, you've got to loosen up a little bit. Have some fun in your life. Accept Cromartie High School into it. You'll thank me later.