Ever since his debut, Sceptile as a Treecko was a cool, calm and collected while holding a twig in the side of its mouth. Sceptile has an overpowering pride, similar to Buizel's, that he will defend at all costs from anyone or anything that damages it, most notably after being defeated by the wild Seviper before Jessie had caught it. As a Grovyle, he was shown to tease the other Pokémon, especially Corphish, although he would always defend and protect them. He is also in love with a Meganium until it realized Meganium is in love with a wild Tropius whom he defeated to gain Meganium's love. When he evolves into a Sceptile, he does his best to save Meganium from Team Rocket but to no avail as his abilities are lost because of his broken heart. He later regains his abilities after getting recovered from being heartbroken.
Sceptile was caught while he was a Treecko in the events of Trees of A Crowd, and was the second Pokémon Ash caught during his journey in the Hoenn Region. In its debut appearance, Treecko is shown sitting in the branch of the huge dead tree after he spits his twig on both Ash and Pikachu who accidentally came to their territory. Treecko demonstrated its abilities by knocking Pikachu with Pound. It reveals that Treecko has a dispute towards the elderly Treecko and its inhabitants who convinces it to move from another tree and Treecko rejects it. Ash and Pikachu helps it to restore the tree back to its former glory until all the wild Treecko including its elder are caught by Team Rocket. Treecko manages to knock off James' Cacnea with Pound causing Jessie to get bumped on the switch to release all Treecko including its elder and Pikachu. Treecko childisly taunts Cacnea long enough to distract it while at the Meowth Balloon with several lights. Eventually, Cacnea accidentally hits the balloon causing them to blast off. When the dead tree is about to rip in half, all of the Treecko tries to protect it until it was cut off to reveal a seed beneath the tree. Treecko finally challenges Pikachu in a battle but was defeated allowing Ash to capture it. Ash finally bid farewell to the wild Treecko and its elder and Treecko happily smiles to them after it joins Ash's side.
In A Tail with a Twist Treecko was a very stubborn fighter who never gave up in battle. This is also demonstrated when it was beaten by a wild Seviper before Jessie had caught it. Despite its near recovery, it trains heavily to break a rock from the falls using Pound and does an improvise move to break it. It manages to defeat Seviper with the same ability before Pikachu blasts Team Rocket off.
In What You Seed is What You Get? Ash trains Treecko to learn Bullet Seed by eating watermelons and spits all watermelon seeds. They are cornered by Natasha a watermelon master along with her Pokemon Grovyle and Slugma. Her Electrode disguised as a watermelon appear it notices Ash and the group are not watermelon thieves causing her mistake. Ash has a double battle with Natasha using Treecko and Corphish against her two Pokemon in her stead. Ash uses Treecko for an advanced training to learn Bullet Seed by fighting Natasha's Grovyle. As both Corphish and Slugma are down, the battle is interuppted by her Electrode who informs her about the watermelon thieves which happens to be Team Rocket using a giant Cacnea robot to steal the watermelons. They are soon attacked by Team Rocket's Cacnea robot with a multiple of watermelon seeds. Ash tells Treecko to watch how Grovyle hits them with Bullet Seed before its mouth were taped by Meowth. Treecko eventually learns Bullet Seed to cut off the sling of the basket to recover the watermelons but temporary as it allows the group to catch the watermelons followed by Pikachu to blast Team Rocket off with its Thunder Bolt. The battle of Treecko and Grovyle resumed as it tries to hit with its Bullet Seed at Grovyle but it was a lack of range and its practice and ends up being defeated by Grovyle making Natasha wins the battle. In the end, Treecko does not accept its defeat and it finally learns Bullet Seed when Ash and Pikachu gave him watermelons and it masters the technique properly by hitting them with efficiency.
In Exploud and Clear, Treecko evolved into Grovyle whilst battling a powerful Loudred, who later evolved into Exploud. It has a strong rivalry with Exploud and tries its best to stop Exploud from its own rampage. In the end, both Pokemon continues to challenge themselves in the battle.
After evolving, Grovyle was used often in the Hoenn region, notably being able to defeat Norman's Slaking and Winona's Altaria despite having type disadvantage against the latter. In the Hoenn league tournament, Grovyle defeated Katie's extremely powerful Walrein as well as Morrison's high-leveled Steelix and held his own against Tyson's Metagross.
Grovyle stayed with Ash when he travelled to the Battle Frontier. When Ash went up against a wild Onix who was also the Rock Pokémon King whose subjects had Brock, May, Max, Pikachu and the other Pokémon in cages, Ash chose Grovyle to battle Onix and in addition to the type-advantage, Grovyle's agility and speed gave it an edge in the battle and a single Leaf Blade was strong enough to cause the battle to go in Ash's favor.
Grovyle was used during his battle with Greta but was defeated by Hariyama.
When Sceptile evolved, it lost its ability to use any of its attacks since its heart was broken when Meganium fell for a wild Tropius instead of Grovyle. After seeing Meganium in danger, Ash's Grovyle evolved to try and protect it to no avail.
Later, Sceptile finally regained all of its moves as well as the new and powerful Solar Beam attack. Sceptile used Solar Beam to defeat Spencer's Claydol. Sceptile was later used in an unofficial battle against Pyramid King Brandon and his Regirock when its trainer was possessed by the King of Pokélantis. However, despite having a type advantage, it lost.
Sceptile is an expert at the move Leaf Blade, its signature move. It was even able to defeat Tobias' Darkrai, who was considered to be virtually unbeatable, with a powerful Leaf Blade, becoming the only known Pokémon to have defeated the legendary Pokémon.
It battled against Tobias' Darkrai during the Sinnoh League tournament. Sceptile fought hard and took serious damage from its Ice Beam attack and then fell victim to Dark Void. But thanks to Ash's voice, it quickly woke up and finished it off with a powerful strike from Leaf Blade. However, Tobias' Latios easily defeated Sceptile with Giga Impact.
It appears (along with other Ash's Pokémon) in the opening scene of BW: Adventures in Unova.
|Pound||Tree's a Crowd|
|Quick Attack +||A Tail with a Twist|
|Bullet Seed||What You Seed is What You Get|
|Leaf Blade +||Exploud and Clear|
|Solar Beam||Ka Boom With a View!|
|Agility||Curbing the Crimson Tide!|
|Leaf Storm +||The Semi-Final Frontier!|
|+ indicates this Pokémon used this move recently.*|
- indicates this Pokémon normally can't use this move.
- Yūji Ueda (Japanese)
- Dan Green (English as a Treecko)
- Darren Dunstan (English 4Kids dubbed as a Grovyle)
- Bill Rogers (English PUSA dubbed as a Grovyle and a Sceptile)
- Sceptile was Ash's first fully evolved -type starter.
- Ash's Sceptile is the only known Pokémon to have ever defeated Tobias' Darkrai.
- He is Ash's third Pokémon to battle and defeat a Legendary Pokémon, the first two being Charizard and Pikachu.
- Sceptile is the only Hoenn starter Pokémon Ash caught, as Torchic and Mudkip were caught by May and Brock respectively.
- Like May's Blaziken, Ash's Sceptile was voiced by Darren Dunstan and Bill Rogers in its evolved forms.
- Out of all Ash's Pokémon, Sceptile holds the record for facing the most Legendaries at three, having battled Brandon's Regirock, Tobias' Darkrai and Tobias' Latios.
- Like Ash's Squirtle who rarely wears its glasses as he keeps it in its shell, Sceptile is mostly seen has a twig on its mouth since it was a Treecko during battles even its evolution.