Gurimo Duels strategically, and appears decently skilled as he was able to defeat both Weevil and Rex at the same time. He shows complete loyalty to the organization to which he belongs. He also appears to like a challenging/skilled opponents, as he called his Duel against Yugi "refreshing" compared to past opponents.
Gurimo runs a Warrior Deck, focused on a swarm strategy. His monsters' otherwise mediocre ATK are increased by both "The Seal of Orichalcos" and "The A. Forces". His Deck and its swarm ability is also able to take advantage of the fact that "The Seal of Orichalcos" allows him to control up to 10 monsters at once, as he places his more vulnerable monsters in the back row to prevent them from being attacked while his more defensive monsters are summoned to the front row. This strategy also can work well with "Obelisk the Tormentor", as it gives him enough monsters to Tribute for both its Summon and effect. However this strategy can also lead to his undoing, as if multiple monsters are destroyed at once, he takes even more damage, as Yugi proved.
In the English dubbed anime, Gurimo's name is never spoken out loud, instead mostly being referred to as "the old man" by Alister and Valon. Eric Stuart, Seto Kaiba's voice actor in the dub, once stated that his dubbed name was "Grerimo", but this was retconned by multiple more recent sources, including Konami's blog, which retain a romanization of his original Japanese name.