This is super ambitious for Newgrounds and I think it mostly comes together in the end! I love the school setting and slice of life vibe. You've created a fully fleshed out world and really filled it out with some fun characters. Not only that, but the amount of animation variety is really impressive. I only have two critiques.
1. The writing, while providing some hilarious gags, felt a bit repetitive. The intro sequence provides everything we need to know and I still kind of felt like we were being reminded of the main motivating factor of why Marcus is trying to stay popular here and there. I feel like editing some of the fat out early on would help a lot.
2. The voice acting is all great, but the mic quality varies a bunch. I'd just work on making sure the consistency is a bit more solid.