Snivy is a proud and seductive Pokémon, and she also has a great observation. Furthermore, she has a sense of justice. When Iris' Emolga is causing mischief among Ash's Pokémon, she always mercilessly exposes Emolga's mischievous behavior by bringing her with her Vine Whip and to show it to Ash and his friends that she was responsible for stealing their apples, which makes Emolga angrily fed up, creating their heated rivalry. Even she barely shows her emotions, she cares deeply for her friends. Still, she dislikes Trainers who don't fit her expectations, especially those who are selfish, which was a reason why she had left her former Trainer.
In Scraggy and the Demanding Gothita! Snivy also dislikes Katharine's Gothita's bratty and demanding behavior when she takes a liking to Ash's Scraggy and her actions to other Pokémon. After she defeats her in battle, Snivy humiliates it by showing her beauty streak towards her.
She is also had a behavior of a femme fatale when using her Attract against male Pokémon which she demonstrated this to Pikachu, Oshawott and Tepig when Ash attempted to capture her. But it didn't affect Pidove due to both having the same gender, making her felt desperate to fight.
Snivy first appeared in Snivy Plays Hard to Catch!, where it was caught by Ash and the gang stealing food from them. Ash then chased after Snivy through all of the episode, using each member of his team in turn to battle her, however the majority of his team (Pikachu, Oshawott and Tepig) were affected by Snivy's Attract, forcing Ash to recall each of them. It wasn't until Pidove offered to battle did Ash manage to hold his own Snivy, as her Attract had no effect on Pidove. Snivy broke out of the first Poké Ball attempt and fought back, but she decided that Ash was a worthy trainer and allowed Ash to catch her.
Snivy is used to fight a wild Gothitelle which is owned by Sally the daughter of the Water Taxi Captain in the episode The Lost World of Gothitelle! when it manages to send Ash, Cilan and Iris to the lost world. Snivy becomes seriously desperate to fight it was later interuppted by a present Sally whom she recognizes her Pokémon who helped her selling juice and cookies as a child. After both Sally and Gothitelle bonded together, the fog is completely gone due to its safekeeping of their memories.
She was sent out twice during Ash's five-on-five battle with Trip in A Rival Battle for Club Champ!. She first battled Trip's Servine and won with the help of her Attract. She then battled Trip's Frillish after Pidove was defeated, leaving her as Ash's only hope. Ash had no knowledge of Frillish's Cursed Body ability, Snivy endures Water Pulse easily, but the resulting confusion results in Frillish's Hex knocking her out.
In Emolga and the New Volt Switch!, she battled against Bianca's Pignite after Iris' Emolga summoned it using Volt Switch. It later develops a rivalry with Emolga, as she is unimpressed with Emolga's mischievous attitude. It continuously uses Vine Whip to bring Emolga back after she tries to escape and also when Snivy showed the gang who had caused the fight between Ash's Pokémon after Emolga steals all of their apples by fooling them using Attract causing her to get mad at her actions. However, despite this, Snivy saved Emolga (as well as Axew and Oshawott) from a wild Simisear. Therefore, she was reluctant to team up with Emolga to save the wild Simisear from a falling rock by breaking it with both Hidden Power and Leaf Storm combination. In the end, both Snivy and Emolga are not looking at each other due to their rivalry.
Ash used Snivy to battle against Trip's Servine again in Ash and Trip's Third Battle!. However, this time her Attract was blocked by Servine's Leaf Tornado and her Leaf Blade was overpowered by Servine's Cut.
In Cilan Versus Trip, Ash Versus Georgia!, Snivy was used against Georgia's Pawniard during the second round of the Don Battle Tournament, however, she struggled against the powerful Pokémon, having Attract fail when Pawniard also turned out to be female. However, she managed to defeat Pawniard in the next episode, by somehow using Leaf Blade to hit Pawniard dead-on while avoiding Guillotine and knocked her out with Leaf Storm.
In Battle for the Underground!, all of the Pokémon were captured by Team Rocket. Snivy used her vines to let out several of the groups Pokémon, all of which proved useful for making an escape. She also used her vines to switch the direction of the tracks, allowing the Pokémon to get away from Team Rocket's train car.
In Dazzling the Nimbasa Gym!, Ash used Snivy against Elesa and her Emolga. Since they were both female, so Attract proved to be ineffective. While Snivy managed to hit it with Leaf Storm, Emolga finally defeated Snivy with several powerful Acrobatics and Aerial Ace attacks.
In Scraggy and the Demanding Gothita!, Snivy was happy to see Axew and Scraggy getting along despite them both losing in a battle. When Katharine's Gothita and Scraggy escaped and then followed by Axew in the middle of the night, Snivy followed them closely, and saves them from an attack caused by a wild Garbodor.
In Battling the King of the Mines!, Snivy was used in a Gym battle against Clay's Palpitoad. She used Attract to immobilized it and then hitting it with Vine Whip and Leaf Blade and finally defeated it with Leaf Storm.
In Beauties Battling for Pride and Prestige!, she faced off against the Flower Garden Trio. Ash used Snivy up against Moira's Cinccino in a test of strength on a balance beam. She overpowers Cinccino and throws her into the mud, later her and Cinccino have a real battle and, although Cinccino gave her serious problems, she managed to defeat it.
In Cameron's Secret Weapon!, Snivy was the sixth Pokémon Ash chose to use during his Vertress Conference battle with Cameron, sending her out to face Cameron's Riolu. Riolu started the battle with a Vacuum Wave, which Snivy was easily able to dodge before attacking the Emanation Pokémon with Leaf Blade. While Riolu tried to struggle to his feet and almost fainted, the severe pain resulted in Riolu suddenly evolving into Lucario, a much more formidable opponent, who got his strength back. Snivy bombarded him with numerous brutal Vine Whips, but Lucario caught them and used Circle Throw, and finished her with Aura Sphere, leaving only Pikachu to battle the powerful foe.
In Team Plasma and the Awakening Ceremony!, she was used to battle against two Golurk controlled by Colress. Despite the notable size difference, Snivy is able to bring them down with Leaf Storm, but she had to be returned to her Poké Ball when Colress turned his mind control device on them.
After Ash's Unova adventure was over, Snivy was left in Professer Oak's labortary.
|Attract||Snivy Plays Hard to Catch!|
|Vine Whip||Snivy Plays Hard to Catch!|
|Leaf Storm||Snivy Plays Hard to Catch!|
|Leaf Blade||A Rival Battle for Club Champ!|
|+ indicates this Pokémon used this move recently.*|
- indicates this Pokémon normally can't use this move.
- She shares traits with Ash's other Grass type Starters: being a protector like Bulbasaur, being female like Bayleef, being a prime battler like Sceptile and taking charge like Torterra, specifically when the latter was a Turtwig. She, like Bulbasaur, also never evolved.
- All of Snivy's Grass type moves are also known by Ash's other Grass-type Starters.
- Snivy has developed a rivalry with Iris' Emolga.
- Interestingly, they are both the only female Pokémon currently on the main cast that know Attract.
- The two have somewhat opposite personalities; Snivy is calm, collected, mature and willing to fight her own battles no matter how tough her opponent may be, while Emolga is childish, deceptive, lazy and unwilling to battle seriously and/or tricks/forces others to battle for her (by using Volt Switch).
- Snivy is Ash's first Unova Pokémon confirmed to be female.
- Snivy's capture marks the first time since Johto that Ash has captured all three of a region's starters.
- When Snivy unleashes her Leaf Blade from her tail. It resembles Ash's Treecko's Pound during execution.