Upon further inspection, making a proper class is actually more intense than you might think. While I did go all out on the characters and it feels like they are pretty diverse while keeping a nice touch of cliche, there are more, not so obvious problems you might encounter. These, on the other hand, are things that most people who once drew manga or at lest tried to, might be familiar with.
Examples:
If you dont manage your haircolors properly, some haircolor (for me, that is blonde for most positive attitudes) will feel too frequent and every time you see your whole class, it feels weird. Going for multiple colors for a single archetype (pink in this example) will greatly help here.
Missing background Information makes the whole Idea problematic. Even though the characters are different from vanilla, since I aim to make them "just like vanilla, but different", after a while, I would suspect that it actually does feel like vanilla. While i personally know how i set up my characters and can somehow relate to them, i guess most people woudnt know the difference. This means that profile information MIGHT be a great tool here. If someone actually makes the effort of reading those before choosing his 'target', reading about his target being his MCs sister-in-law or his otaku MC having a terrrible case of chuunibyou, which is causing him to be rather antisocial and bad with girls, might just work wonders on immersion.
Sizes. All sizes, be it character size, breat size or waist size, should have a common median around the middle. If personal preference is used to create the characters, these things will obviously be great for one person, but feel terribly out of place for another. The class should be as diverse as possible, including characters the creator did not think of as "great". This, of course, is a big problem, since that is not something you usually go for when creating something.
Consider how many traits are necessary. I personally feel obliged to use 2 traits every time, but that is of course not true. If your characters only real important feature is being a tsundere, go for it. If a character is supposed to be as "normal" as possible, maybe consider "ordinary" + no traits at all.
Eyes. Tinkering with the eyes is great fun. Dont go about making every character have the same pair of eyes. In most manga, they are part of describing the characters personality, so try to do that. Sharp edges and a bit smaller for tsundere, wide and round for refined characters. These things are needed to create proper characters.
Finally, its important not to go with the flow on every aspect. "Weird" characters make anime all the more interesting to watch, so remember to include some of those also. A quiet tsundere? Why not? The outcome might be interesting. Dignified with no virtue and perverted? Uncommon, but the outcome might also be interesting.
[Edit+attachment]
Gotta have friggin twins in your class