Guab is the alien pet of Aunty Gravitee and the guard of her prisoners who have to participate in her freakshow.
He can't talk and is very small. He has a yellow skincolour and a round shape. When he has to tackle someone he grabs the person in his mounth and spits him out. His vomit is a very strong stuff where even Robotboy couldn't escape from in his normal mode when he was eaten by Guab.
When Gus and the other aliens escapes, they capture Aunty Gravitee and Guab.