Grimsley is on Route 4 because he, presumably, has information regarding Team Plasma and has decided to set a trap for them there. He wears a hood and cape, concealing his identity as he plays card games with the construction workers to entertain them during their lunch break.
When Black approaches him afterward, Grimsley invites Black to play a different game with him: Bisharp makes a line in the sand, and he and Black have to try and guess which side of the line a drilbur (perhaps belonging to a construction worker) will surface on. He doesn't tell Black that this game is a trap for a Team Plasma member, as he specifically told all the real workers not to come go over there. A Team Plasma falls into the trap (literally, as Drilbur has been burrowing around). Coincidentally, Grimsley wins the drilbur game against Black at the same time, the final score being 4-3.
Black demands to know why Grimsley is here; Grimsley claims he doesn't have a problem with telling Black, but makes it into a bet: if Black wins, Grimsley will tell him why, while if Grimsley wins, Black will have to give up his most precious items, because that information is important to Grimsley. When Black passes out from indecision, Grimsley is concerned and then realizes that Black was debating whether to bet his badges. He says that not betting his badges is the right decision and leaves while Black is unconscious, but not before finding a flier about Relic Castle in the Team Plasma member's possession. Grimsley leaves a note with the Team Plasma member, saying that this man is a bad guy and you can do what you want with him.
Grimsley presumably goes to Relic Castle.
Grimsley is next seen at the Pokemon League with Shauntal and soon joined by Caitlin and Marshal as well. They talk about Alder losing to N and then disappearing, as well as Team Plasma becoming a problem. Marshal tries to convince them but Caitlin refuses and so does Grimsley saying he'll only protect himself if necessary.
Grimsley tells Black that the reason he's at Route 4 is to entertain the workers on their lunch break, and he does, which is a kind thing to do; however, he's also laid a trap for a Team Plasma member, demonstrating kindness, cleverness, and an ability to lie (or at least omit the truth). He also tells Black that anything can be a game, which can improve your Pokémon battling skills. Grimsley also shows a propensity to treat things as games and to bet.
When he makes a bet that if he loses to Black, he'll tell Black why he is at Route 4, it is a pretty safe bet (considering he's an Elite Four), perhaps concealing vital information as trivial. When Black faints, Grimsley shows concern; and when he realizes Black dilemma about whether to bet his badges, Grimsley thinks that Black could have bet something else, and that not forcing himself to bet his badges was the right choice.
Grimsley says it's his style to only look out for himself.
Grimsley seems to like Black, for what it's worth. He plays the drilbur game with him and acts rather friendly. When he realizes that Black has fainted because he couldn't decide whether or not to bet his "most important thing," his badges, Grimsley seems to admire his all-or-nothing personality, commenting that Black could have chosen to bet something less important to him. He seems sort of resigned but happy as he says that he and Black will meet at the Pokémon League.
- Grimsley is very good at cards and other games
- He has been a casino dealer for over ten years