Buddy Packs were invented by Machete, and were one of his many inventions. They are jet packs that resemble robots.
In Spy Kids, Juni discovered a line of them at the safehouse. A group of Floop's goons grabbed the packs and escaped with the Third Brain. Carmen strapped on another to chase after them and retrieve the brain. Juni attempted to as well, however the Buddy pack started up and slipped out his hand. The Buddy pack ended up burning Miss Gradenko's hair.