Here's a non-shitty translation of the summary that should clear up any of your misconceptions. It's a bit loose and doesn't follow the structure of the original, but should do its job.
"During the battle with Shootie, Satoshi discovers that Mijumaru's weakness is its inability to hold its eyes open under water. He immediately heads for a pond to train Mijumaru, while leaving his other Pokemon under Iris' supervision, but the training is not successful. While Iris is playing with the Pokemon, waiting for Satoshi to return, Zuruggu headbutts a clump of grass where a group of Tamagetake is hiding. They get angry and sprays the Pokemon with Poisonpowder. Being that there's no Pokemon Center nearby, their only solution is to retrieve some herbs from the botton of the lake to cure the poison. Mijumaru goes to retrieve these, but the Gamagaru and Muggyo living in the pond don't take kindly to intruders."
Pro tip, adyniz: Tossing the summary into google translate and rewording the result into semi-coherent English is not translating.