Ben 10 season 1 episode 12 : Side Effects

Councilwoman Lang's tries to develop a downtown area in the city again, which disturbs a man named Clancy. As Upgrade, Ben tries to stop a villain. He finds an ice cream truck and gets in it, but gets trapped in there when getting an ice cream. Now he has a cold and what's worse is that the Omnitrix and his forms are weakened by the cold. When Clancy makes threats to the city by causing a meltdown at a power plant and captures Councilwoman Liang, Ben attempts to stop him while dealing with his cold's side effects.