Since Gir was so popular, here’s Zim in Fate Accelerated Edition terms.
High Concept: I am Zim! This one is self-explanatory.
Wooooo! Step 1 went smoothly! Zim’s plans often don’t work quite as well as he thinks they did. Invoke to help make a plan work out well, compel to ruin it spectacularly.
Gir! Earth is our enemy! Zim doesn’t understand many things about Earth. Invoke when Zim establishes a fact that isn’t true (like Yes, arm control nerve!) or compel to have something about Earth work against him (So, this rain… is it poisonous?).
Humans and their filthy friendship! Zim acts like he doesn’t need any help from human friends. Invoke when Zim wants to exploit human relationships, compel when he needs to work with humans.
My squeedly spooch! Zim has Irken physiology. Invoke when something that should affect a human does not affect him, compel when his physiology causes him problems.
Paranoid: Fair (+2)
Devious: Good (+3)
Brainy: Average (+1)
Competent: Mediocre (+0)
Brilliant Disguises: Like Gir, when Zim is in disguise no one notices that he is not human.
Irken Technology: Zim has access to all manner of devices including his PAK and his voot cruiser. Once per session, choose one Approach and gain a +2 to using it for the session.