Ben 10 season 3 episode 6 : Game Over

Ben and Gwen are playing Sumo Slammer video game and Gwen is beating Ben at it. As a result, Ben turns into Upgrade and merges with the computer so he can lower Gwen's score. As Gwen tries to get Ben out, lightning hits the van and zaps them both into the game. It isn't long before they realize that all of the aliens in the Omnitrix are unavailable and they have to collect tokens in order to activate certain ones. They progress through the levels in order to get the Upgrade token and allow them to leave the game. However, the villain of the game hears them, and wants to use the Upgrade token to leave the game and take over the real world.