Ash spent some time in the Safari Zone in the episode The Legend of Dratini. He was attempting to catch as many Pokémon as possible, though all he ended up with were thirty Tauros as they always ran in front of his Safari Balls when he tried to make a catch. At the end of Ash's adventures in the Safari Zone, all thirty Tauros were sent to Professor Oak's laboratory. This episode has never been aired outside of Japan due to the firearms being a plot point. The dub merely mentions in Showdown at the Po-ké Corral that Ash caught the Tauros in the Safari Zone without the captures ever being depicted.
The Tauros' main characteristic is stampeding. This means that the lab is a good place for them, as there is plenty of space to run around. They have proved useful at the laboratory, stampeding to wake up Ash's Snorlax in times of crisis. However, the stampeding has caused mishaps. The first time Ash returned to Pallet Town, they stampeded through a fence. Later, they stampeded through the lab, leaving a mess and a large hole in the wall.
Ash began using Tauros when he needed a replacement for Snorlax for his battle for the Winner's Cup of the Orange League in Hello Pummelo and Enter The Dragonite. He sent the now-sleeping Snorlax to Oak's for one of his Tauros to see if the "beginner's luck" strategy he had used in the Indigo Plateau Conference with Kingler and Muk would work again. After an initial failure when hit with Gengar's Confuse Ray, Tauros managed to defeat a Venusaur on his own during the battle, subsequently helping to weaken Drake's Dragonite for Pikachu to land the final blow. He then stayed in his Poké Ball until Ash returned him to the herd when he returned to Pallet Town.
The Tauros was used again in early Johto during the Pokémon Swap Meet. One of the events was a Tauros-battling competition, which Ash entered after exchanging Heracross for Tauros. He ended up winning the competition — subsequently receiving multiple offers to trade Tauros before he explained that he wasn't there to trade — but sent Tauros back to Professor Oak in the next episode. Ash later used a Tauros in the Silver Conference, where it was defeated by Gary's Nidoqueen.
In the special episodes, they made a cameo appearance telling the other Pokémon about Cassidy and Butch.
On Ash's return from Hoenn, the Tauros were seen running towards him with his other Pokémon. However, they were just stampeding as usual, and Ash had to be rescued by his Bayleef before he could be reunited with the other Pokémon. He used Tauros again in the battle against Salon Maiden Anabel in Talking a Good Game! and Second Time's the Charm.