Chaos Drives are crystalise chaos power that are usually contained in devices. they seem to be power source for most robots.
Sonic Adventure 2
Original Chaos Drives, as discoverd inside GUN robots.
Chaos Drives first appear in Sonic Adventure 2 as power source for GUN Robots much like animals used for Eggman's robots. Collected and used with chao at Chao Gardens to enhance a chao specific skills.
Red for Power
Yellow for Swimming
Green for Running
Purple for Flying
With the right combination of animals, colour of Chaos Drives and depending on who is raising the specific chao can alter the outcome of the chao to appear simular to a character.
Sonic the Hedgehog (2006)
They appear once again along with Light Cores. Light Cores can replenish a bit of energy to the Action Gauge while Chaos Drives restore the most. Incidentally Chaos Drives also appear as a Power Up on item boxes. Once the item box is busted it will fully restore the Action Gauge. Unlike Sonic Adventure 2 where Chaos Drives slowly fall to the ground and you pick them up, Light Cores and Chaos Drives home into you the moment the robots are destroyed. They are not used for chao care.