Mini Moose

Mini Moose is a supporting character in The Most Horrible X-mas Ever of Invader Zim and a major antagonist of the 2019 Netflix film Invader Zim: Enter the Florpus. It is a robotic moose created by Zim who has grown tired of GIR's stupidity and made a replacement sidekick, but still keeps him.

Personality
Mini Moose is either somewhat diabolical and mischievous or innocent and carefree like GIR. Because Zim was originally going to install an Obey-o-nator-2000X, the most unquestioningly obedient computer brain in the galaxy, but Zim wanted it to be even more unquestioningly obedient.

In Enter into the Florpus, the Mini Moose thinks Zim is cool but apparently isn't above using his oratory skills to trick Zim in order to get out of trouble, suggesting that Minimoose has a manipulative side.

Invader Zim
Mini Moose first appeared in The Most Horrible X-mas Ever where it helped Zim to formulate a plan to destroy the humans during Christmas, but failed because of Zim being freed by Dib from the suit, accidenatally killed Santa Claus. Zim, now dressed as the "Easter Platypus", convinces the human race that Dib killed Santa and they all tackle him.

Invader Zim: Enter the Florpus
Minimoose has a major role in the film, as Zim stated that he's the "only being in the known universe" to have the ability to channel cosmic energy into the Membracelets, which is key both to Zim's plan to transport Earth into the path of the Irken Armada, and later to enabling Professor Membrane undoing it. After the latter occurs, Zim initially blames Minimoose for his plan's failure, but quickly forgives the moose.

Trivia

 * Unlike Zim or GIR who needs disguises to conceal their identities from the humans, Minimoose technically doesn't necessarily need one since the resembles an Earth creature and doesn't have to worry about keeping its abilities hidden since most people are oblivious.
 * At the end of Enter the Florpus, a car can be heard parking just before Minimoose enters Zim's Base, implying he was driving one. How this is possible when he lacks the limbs to drive is unknown, and it's probably that this is just a joke and not meant to be taken seriously. On the other hand, as mentioned above, Minimoose has some telekinetic powers which could be how he was able to drive the car, and previously in the Christmas special, he was seen piloting a labor sleigh.