I wish I could give you more examples of dramedies, Samurai Jack is a good example and starting point. Here's some advice you can keep in mind when writing a dramedy.
An important part of writing is striking a balance between different elements. If you want to write a dramedy, it's a good idea of when and where you'll focus on each element, whether its drama or comedy. I think a good place to start is to develop the drama of the story. What is the main conflict and how does it affect the characters and the world the characters live in. What are the consequences of the conflict and how does it breed tension between characters.
From there you can consider comedic situations. Is it going to be a Samurai Jack situation where he is the straight-man in a wacky and interesting setting. Maybe the comedy comes solely from character interactions, meaning you have to really develop their personalities. Will the story include physical comedy, satire, or cut away gags, etc. Really, this all depends on the story and characters.
The hardest part of writing a dramedy is integrating the drama and comedy. One model to go by is when you have a lull in one aspect that's when you bolster the other. So for example let's say your characters just got back from a comedic, lighthearted field trip and they are settling into the school routine again. Then out of seemingly nowhere, the teacher drops a test onto the class the day after they get back and most of your characters had been on the verge of failing. Boom, drama and tension. There's tension until the test is over then there's some comedy as they wait for results. They get their grades back and now there's drama again because all the characters failed the test.
It's just a matter of balance and understanding what the story needs and when. Hope this helps.