Emerald's Sceptile is one of Emerald's strongest Pokémon. He is male.
He debuts in Chapter 182.
Ruby considers Treecko as a starter Pokémon but then rejects him from disgust with Treecko's ugliness.
Professor Birch takes Treecko to give to a trainer but loses him due to a tsunami and flood. Floating in Professor Birch's bag, in his pokéball, Treecko is rescued by Wally, who takes him to training in Sky Pillar. Treecko evolves while saving Wally from a wild Dusclops.
At some point, Grovyle becomes a rental Pokémon at the Battle Factory and evovles, though not necessarily in that order.