Well, guys, Mr. Utah answered my question I can't seem to find an answer for, "Are the Tankmen open source/public domain?" Mr. Utah says they are not, they are just as much under copyright as Felix the Cat. But that does not mean I can't make animated series about them, it just won't be for streaming but for free like YouTube, here on Newgrounds, and nonprofit streaming services like Twitch. But I will make it if I get hired into an animation studio that makes web content. (Which is pretty much every small animation studio) And I will likely make the "pilot" as my senior project.
Peonycreme
Was not expecting Mr. Utah to pop again, I thought he was too busy to talk to anyone. (Even me) But he proved Reddit was right and he's one of the only people who can legally pitch a Tankmen series. (the question is, does he or even any of the Newgrounds staff want to? Probably not) But I can make a Tankmen series that is free to watch on online and will do it if I get the opportunity to make a web-exclusive animated series if I get hired at a small animation studio.