After winning at the Mauville gym against Wattson and earning the Dynamo Badge, Ash and the gang decide to travel to Fallabor Town for May's next Pokemon Contest and then to Lavaridge Town for Ash's next gym battle. While traveling, the gang stumbles upon a watermelon field. This gives Ash an idea to teach Treecko how to use Bullet Seed, ever since that battle with Shiftry (Season 6, Episode 37), by spitting watermelon seeds for practice. Suddenly a Grovyle attacks the group as a misunderstanding. The girl then apologizes for her mistake and shows them around the field. Team Rocket then appears to steal the watermelons from the field. Grovyle tries to fire bullet seed but they sealed up its mouth with some tape. So it's all up to Treecko. Ash believes that Treecko can use Bullet Seed, so it tries but fails. The second time around it works and sends Team Rocket to blast off again. In the end, Ash spits seeds towards Treecko and makes it mad and uses Bullet Seed.
—Anonymous