h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Love the concept and what you are doing with it; but we've probably only got one shot at this, so...:

[Invader ZIM is an eccentric alien soldier]
Minor suggestion: 'eccentric and clueless alien soldier'

[ a planet with the unlikely name of Earth,]
Minor suggestion: ' an unidenitifed planet represented only by a yellow sticky at the edge of the map that turns out to exist with the unlikely name of Earth,'

[a somewhat insane paranormal researcher,]
Minor suggestion: 'a somewhat insane, would-be paranormal researcher,'

[Zim was Johnen's first foray into cartoon animation,]
You may want to mention that it was Nickleodeon that asked him to create a cartoon for their network, and that this has confused him ever since. He assumes that they must've never seen his work.

[Apart from the trailer and the unaired pilot, the episodes currently known to me are:]
'Apart from the trailer and the unaired pilot, the episodes currently known are:'
Removing the 'to me' may make it E.G. worthy.

[Aparrantly after this point ]
'Apparently, after this point '

[so I'm not going to bother finding anything else out about them either.]
Again, removing the self-reference will make for a better opportunity to include this in the Edited Guide.

[Zim was trained from an early age as an Irkan soldier, ]
No need to really change this, but he was kinda hatched, wasn't he? He was immediately fitted with his backpack device and could speak.

[ begins his mission of Earth's annihilation.]
More correctly, Zim works toward 'conquest' rather than annihilation.

[He especially likes to watch the Scary Monkey Show, and singing the Doom Song.]
Gir also finds most any show his 'that's my favorite show!', even static.

[Dib is the only human10 to notice that Zim has green skin, no nose, no ears, antennae, and pink eyes. ]
At first, and most of the times Dib sees Zim, the antennae are covered with a bad wig and his eyes are covered with human eye looking contacts.

[He just happens to be a paranormal investigator, so ]
'He just happens to consider himself a paranormal investigator, so '

[Unfortunately for him, all the other kids in his class think he's crazy,]
' all the other kids, as well as the possibly alien teacher, in his class think he's crazy

[He loathes Santa Claus.]
'He loathes Santa Claus and loves toast.'

[when he drinks the last soda. ]
'when he drinks the last soda or worse, eats the last slice of pizza!'

[they like candy. ]
'they like candy, really all snacks, and puppets; they really like puppets.'

I hope this helps.