She and Pierre were trying to determine whether Sudowoodo was a Rock-type or a Grass-type. She argued that knowledge written in books is not always right. During their field research, Marie witnessed Sudowoodo perform the moves Razor Leaf and Vine Whip, which is impossible for any Rock-type Pokémon to learn, therefore she concluded that Sudowoodo was a Grass Pokémon. Eventually, they learned Sudowoodo was in fact a Rock-type after noticing the wild one they were studying was afraid of water, which is abnormal for a Grass-type Pokémon. With the use of the move Mimic, Sudowoodo was able to imitate moves not of its type.
Her grandfather was inspired by Marie's hope in finding a Sudowoodo and was willing to offer anyone who caught a Sudowoodo on his behalf a trip to the other side of a river with his boat.