You know, if I make this fight, my headcanon is that the Vilgermites and the Irkens are rivals in conquering the cosmos (tho the Vilgermites don't see the Irkens as much of a threat due to them being a bunch of idiots).
The story would start with Zim's computer informing him of another alien. Zim would think of it as another Irken, only to find out to be... a Vilgermite.
Zim go to (whatever the hell Omni-Man lives at) and starts to attack the place. Nolan would instantly recognize the Irken technology and remark as something like this: "I didn't know that Irkens would reach out this far. Either this is their best invader... or an absolute idiot."