He is noted to have developed skills for the sport surprisingly quickly, believing that it couldn't be much different from riding a Sharpedo. In Ultra Sun and Ultra Moon, Grimsley is an accomplished Mantine Surfer, where he competes under the name Big G (Japanese: ビッグG Big G) and holds a high ranking on the leaderboards of all four islands' beaches before the player has a chance to beat the records.
He also participates as a Trainer in the Battle Tree. Grimsley, having stepped down as an Elite Four member, reappears in Pokémon Sun and Moon and Pokémon Ultra Sun and Ultra Moon at Route 15, where he assists the player by registering Sharpedo into their Ride Pager. As a result, he developed a gambling addiction. He is the son of a distinguished family that fell into ruin. In Pokémon Black, White, Black 2, and White 2, Grimsley appears as an Elite Four Trainer of Unova. 6.3 Pocket Monsters BW: The Heroes of Fire and Thunder.1.1.3 Pokémon Sun, Moon, Ultra Sun, and Ultra Moon.1.1.2.3 Rematch (Easy Mode/Normal Mode).1.1.2.1 First battle (Easy Mode/Normal Mode).1.1.1.2 Rematch (post-National Pokédex).1.1.1.1 First battle (pre-National Pokédex).Pokémon Brilliant Diamond and Shining Pearl.
