Prior to the series, Mallow met Steenee as a Bounsweet in the forest behind the Pokémon School.
Steenee first appeared as a Bounsweet in Alola to New Adventure! alongside her Trainer. Bounsweet accompanied Mallow on her tour of the Pokémon School for Ash and Pikachu, happily sharing her pleasant scent for them to enjoy. She later watched Team Skull battle Kiawe. The following day, Bounsweet attempted to play with Lillie, scaring her in the process. She later watched Ash and Pikachu's battle against the guardian deity, Tapu Koko.
In First Catch in Alola, Ketchum-Style!, Bounsweet was attacked by a wild Rowlet, who was attracted to her scent and mistook her for a fruit. Bounsweet quickly responded to the attack, deflecting the Rowlet multiple times with ease before it tired out.
In A Seasoned Search!, Bounsweet helped Ash and Mallow lure in and subsequently follow a wild Oricorio to the Melemele Meadow, so that they could collect the Nectar necessary for the food Mallow was trying to perfect. However, soon after finding the meadow, they were attacked by Team Rocket, who tried to steal the Nectar for themselves. In order to save everyone, Bounsweet attacked Team Rocket and proceeded to evolve into Steenee. This allowed it to recover the stolen Nectar, free Ash and Mallow, and defeat Team Rocket.
In When Regions Collide!, Steenee was used in a battle against Misty's Psyduck alongside Lana's Popplio. Steenee started the battle with Magical Leaf while Popplio quickly followed with Bubble Beam. Psyduck then counterattacked with Water Gun. Popplio then created a water balloon, absorbing the Water Gun, which it then launched at the Duck Pokémon, trapping it inside. Misty commanded Psyduck to use Confusion, but Psyduck didn't respond. Steenee then attacked with another Magical Leaf, breaking the balloon and causing Psyduck land on its head, giving it a headache. This allowed Psyduck to successfully use Confusion, but before it could do anything more to its opponents, Misty told Psyduck to put Popplio and Steenee down, saying that they had had enough.
In Rescuing the Unwilling!, Steenee was among those used to fight Lusamine's Mismagius, Milotic, and Lilligant, which were under Nihilego's control, to allow Ash to save Lusamine. Going up against Milotic, Steenee countered its attack with Double Slap. Lilligant then made her dance with Teeter Dance, but Ash's Litten and Rowlet released her from the dance, joining the fight. Lilligant drew Rowlet towards her with her Sweet Scent move.
In 10,000,000 Reasons to Fight!, Steenee emitted her own Sweet Scent to bring Rowlet back to her. She then launched Rowlet into the air with her Double Slap, and asked Mallow to throw her up as well. Steenee kicked Rowlet back towards the ground, and, combined with Rowlet's high-speed Peck attack, they used a move Lana dubbed "Rowl Launch" on Lilligant. The attack angered Lilligant, causing it to charge up its Solar Beam attack, but Litten interrupted the move with Fire Fang. Although Lilligant appeared to have been defeated by this move, Nihilego made it get back up and continue battling.
Steenee is a friendly Pokémon, happily interacting with people and Pokémon. She is not easily discouraged, staying positive even after Lillie was frightened by her attempts to play with her. She has a strong relationship with her Trainer. As a Bounsweet, she was normally seen resting on Mallow's shoulder. Steenee also likes to help Mallow out at her family's restaurant, serving food to customers as the restaurant's poster Pokémon. In addition, she loves flowers, as shown in The Ol' Raise and Switch. She likes the floral patterned Poké Beans.
Steenee is shown to be very agile. As a Bounsweet, she often used her quick reflexes to deflect Rowlet as it flew toward her. However, after she evolved, she displayed this trait much less often. This is because she no longer needs to worry about being consumed by other Pokémon.
