Sniffler debuted in Wow!! That's One Big Pokémon as a Sobble. It was first seen as a passenger on Professor Magnolia's trailer car.
In Crackle!! Practice Battle, Henry and Casey fought a trio of Drednaw that gave the trailer car a flat tire. When Sobble wandered onto the battlefield, it was attacked by a Drednaw, causing it to cry. Sobble's tears made Drednaw cry as well, leaving it open to be taken down by Henry's Twiggy. Afterward, the group noticed that Sobble had taken a liking to Marvin and suggested he catch it. Marvin happily accepted and added Sobble to his team, later giving it the nickname Sniffler.
In Toasty!! Battle Against Toxapex, Sniffler was used to train with Twiggy to prepare for Henry's Gym battle with Nessa. Though Marvin cut the battle short, Twiggy gained enough experience to evolve into a Thwackey.
In Rising!! Opal of Ballonlea, Sniffler evolved into a Drizzile during a training session for Henry's upcoming Gym battle with Opal. With its newly-obtained ability to create exploding water balloons, Sniffler helped Henry devise a strategy for avoiding Opal's Gigantamax Alcremie's attacks.
In Chomp!! It's Dracovish, the group traveled to Route 9 Tunnel, where a Dracovish had been reported to have Dynamaxed despite the area not being a Power Spot. They found Dracovish being attacked by several Trainers under orders to either catch or get rid of it. With quick thinking and Sniffler's tears, Marvin kept the Trainers distracted long enough for him to catch Dracovish and escape. At Henry and Casey's suggestion, he decided to keep Dracovish and nicknamed it Draco.
In Crunch!! Snowy Battle, Sniffler was used to battle Gordie's Stonjourner, but the battle was called off when Casey mistook Gordie for an attacker. She borrowed Sniffler and Twiggy and had them team up with her Raboot to create a combination attack that took down Stonjourner. Afterward, the misunderstanding was cleared up.
In PASS34, while Henry was training Kubfu, it got overwhelmed by a group of wild Skwovet and Greedent. Sniffler, alongside Twiggy and Bit, protected it from the Greedy Pokémon. All three evolved during the fight.