The history of this incarnation of Niels, a.k.a. Hairball, most likely mirrors that of his Earth-616 counterpart. At some point in the past, he joined the animal superhero-team the Pet Avengers.
As part of his grand plan to trick Power Pack into going to Asgard and get the Golden Apples of Idunn for him, Loki send a pack of Wargs to attack the Pet Avengers in Central Park. Power Pack noticed the battle while on the roof of the hospital in which their Grandmother was hospitalized, and came to the Pet Avengers aid. Together they were able to subdue the Wargs. With the Wargs now under their command, Throg used his powers to open a gateway to Asgard for Power Pack.
Later, when Loki's plan accidentally set Ragnarok in motion and awoke the giant serpent Jormungand, the Hairball and the other Pet Avengers travelled to Asgard to aid Power Pack and Thor in battle against the monster.
Seemingly those of Niels (Earth-616)#Powers.