In the movie, Shaymin is known as the Gratitude Pokémon. After Shaymin was accidentally pulled into the Reverse World by Giratina and got caught in the middle of the battle between Dialga and Giratina, it used Seed Flare to create a portal out of the dimension. This strange experience caused Shaymin to become terrified of almost everything. It also constantly referred to Gracidea, and was convinced that Giratina wanted to eat it when the Renegade Pokémon really wanted to use Shaymin to open a portal to the real world.
Shaymin found its way to Ash and his friends after its frightening ordeal with Giratina, attracted by the panackes Brock had prepared. Ash, Dawn, and Brock agreed to take Shaymin to Gracidea, where it and its friends would all change Forme together. However, Zero took notice of Shaymin's ability to make a portal connecting the Reverse World and the real world and made several attempts to seize it, hoping to use Shaymin's power to capture Giratina. With the help of Ash and his friends, Shaymin transformed into its Sky Forme after being exposed to the Gracidea and drove away Zero's Pokémon. Eventually, Zero was defeated permanently when Shaymin, Giratina, Ash, and Ash's Pokémon followed him into the Reverse World and put a stop to his plans.
After peace had been regained, Shaymin's friends arrived at Gracidea and joined it as they all changed to their Sky Forme and flew away together.
Shaymin appeared during the ending credits of Arceus and the Jewel of Life in its Land Forme. It was seen climbing up to a tree branch overlooking a forest and then smiling at the sunrise.
Personality and characteristics
Shaymin covered in flowers
Shaymin's personality changes depending on which Forme it takes. In its Land Forme, Shaymin is very fearful, timid, and rather pompous while it is brave, outgoing and friendly in its Sky Forme. It uses different speaking dialects in each Forme in the Japanese version, while in the English dub, Land Forme has a feminine voice and Sky Forme has a slightly masculine voice. Shaymin would transform into its Sky Forme when it came into contact with Gracidea pollen. It would revert to Land Forme at night or when it was exposed to ice. It is able to communicate with other people through telepathy, although it does make verbal sounds as well. It also likes Dawn's Poffins.
Contrary to its cute appearance, Shaymin actually had an incredibly large ego and would boss people around. While Dawn liked Shaymin despite this, Ash said that Shaymin was mean and would explode randomly. According to Shaymin, it would only "explode" when someone mean like Ash was around. Shaymin enjoyed being held by Dawn and also riding on Ash's head. It wouldn't move from there as it wanted Ash to also suffer if it was in trouble. Due to all this, it appeared that Shaymin and Ash disliked each other.
After Shaymin made it to Gracidea, it admitted it never truly disliked Ash. It was grateful to Ash and his friends for all that they had done for it and after bidding a tearful farewell, it joined the other group of Shaymin at its home as they changed Forme and flew away.