Grotle first appeared as a Turtwig alongside his Trainer in On the Shores of Success! Having witnessed Lewis battling a wild Oshawott, Nate decided to have a battle with him, sending out Turtwig to battle Lewis' Aipom. After a hard-fought battle, both Pokémon ended up knocking each other out.
Turtwig took part in the battle against Team Plasma in Crisis in the Cold! It battled a grunt's Patrat and won.
In Going Solosis!, Turtwig briefly battled a wild Solosis, but was incapacitated by Hypnosis. He later witnessed Nate catch the Solosis.
In Pokémon - The Musical!, Turtwig, alongside the rest of the group's Pokémon, took part in a Pokémon Musical.
In A Museum Piece Battle!, Turtwig participated in a battle against Lenora and her Watchog. Being pinned down by Watchog's attacks, Turtwig evolved into Grotle. With his new defensive capabilities, Grotle was able to easily withstand Watchog's Iron Tail and strike back with Seed Bomb. Grotle then demonstrated that he had learnt Curse, further boosting his Attack and Defence and allowing him to defeat Watchog.
In Speed is the Essence!?, Grotle was used by Nate in a battle against Geoff's Monferno. During the battle, Monferno's superior speed was proven to be a huge problem for Grotle, who's bulky body prevented it from moving as it wished. Despite landing a few hits on Monferno with Energy Ball, Grotle was eventually defeated by a Mach Punch.
That night, Nate and Grotle began training together. Knowing that Grotle's body prevented its speed from being raised too much, Nate decided to focus on its defensive powers. With help from Lewis and Aipom, Nate and Grotle trained into the night and challenged Geoff and Monferno to a battle the next morning. This time, Grotle was able to hold its own against Monferno's attacks instead of attempting to outmanoeuvre it. After being hit with Monferno's Mach Punch once more, Grotle suddenly learnt Heavy Slam. With its heavier body boosting Heavy Slam's power, Grotle was able to knock out Monferno, proving to Geoff that the faster Pokémon isn't necessarily the better one.
Turtwig is shown to a friendly Pokémon, quickly making friends with the other Pokémon in the group. He takes battling very seriously and refuses to give up, no matter what. This trait was largely seen in his battle against Lenora's Watchog. Grotle's personality remained very much the same when it evolved.