Dario's only appearance was in The Flame Pokemon-athon!. He wanted to beat Lara Laramie in a Pokemon race at any cost. He recruited Team Rocket to break Lara's arm, but did not realize that Ash would be entering the race for her, riding on her Ponyta.
With the help of Team Rocket, Dario went into the lead in the race. His Dodrio's three heads would not stop fighting over eating the fast food. When Team Rocket attacked Ash, Dario took the lead again, his Dodrio obviously had calmed down.
It looked as though Dario was about to win the race, but out of nowhere Ash caught up to him. Dario had his Dodrio peck Ponyta, but it only hurt Ponyta for a little bit. Ponyta later evolved into Rapidash and defeated Dario by a few centimeters.
Dario was furious that he lost and ordered his Dodrio to attack Rapidash. Rapidash easily defeated both Dodrio and Dario by giving them a strong kick, which sent them flying through the air and landing in a spot where Team Rocket was standing.
Blaming Team Rocket for his loss, Dario ties them to a tree and has Dodrio peck them. What happened to Dario after that is currently unknown.
- Dario and his Dodrio are two of few Pokemon characters besides Team Rocket who are sent "blasting off". Nastina is another.