Grumblemon first appeared in episode 6 of Digimon Frontier when he attacked the heroes. In episode 11, he used a Golemon as his minion.
After his Beast Spirit got taken away by BurningGreymon, he ordered the other Evil Hybrids to help him get his revenge on the Digidestined for stealing his Beast Spirit. Despite that, he was ultimately destroyed by MetalKabuterimon.
Later on, he returned in the episode, "Glean Eggs And Scram". He became good with the heroes to fight the Royal Knights.