Verona first appeared to Ash and Brock, warning them not to enter the forest because of a Tangrowth that uses Absorb. They then informed her that Dawn had already gone into the forest with her Mamoswine. Verona assisted them in searching for her. During their search, the aforementioned Tangrowth attacked them and used Absorb on Grotle, sapping its energy. Strangely, after it took Grotle's energy, it left behind a Sitrus Berry to help it recover.
Verona eventually realized that the energy Tangrowth was taking from the Pokémon was being used to help a dying tree. Tangrowth never meant any harm to the Pokémon, which was why it would leave behind either an Oran or a Sitrus Berry so that they would get better.
After the tree became healthier, Verona decided to work with Tangrowth in order to protect the forest.
Verona befriended this Tangrowth in the wild where it lived with other Grass Pokémon. This Tangrowth often absorbed the energy from other Pokémon then left a Berry to it for the Pokémon to eat and heal. Later on, it was discovered that Tangrowth and the other Grass Pokémon were just trying to give back life to the tree that they live in. The Grass Pokémon were using Growth on it using the energy that Tangrowth absorbed from other Pokémon.
This wild Bellsprout is one of the group of Grass Pokémon in the forest that was trying to restore the life of a dying tree where they live. Along with the other Pokémon, it used Growth on the tree so it would not die.
This wild Seedot lives in a forest along with other Grass Pokémon. Deep in the forest, it helped Tangrowth absorb energy from other Pokémon. Cherrim, Bellsprout, and Shroomish usually helped it in taking down a Pokémon.