You hit them with the Chimp-o-Matic! I always wanted one.
The Chimp-o-Matic is a weapon manufactured by Grummel Net Industries (originally designed by their engineers as a party gag to alleviate their boredom) in A Crack in Time. It fires a beam that transforms organic enemies into chimpanzees, and robot enemies into toy monkeys with cymbals.
The Chimp-o-Matic is acquired when completing the challenge "Overkill" in the Agorian Battleplex and winning the Raritanium Cup, and can be upgraded to the Chimpositron with use. In challenge mode, the Omega Chimpositron could be purchased for 501,000 bolts.
The Chimp-o-Matic is a small, light green pistol with a large yellow dish and a blue beam from which it fires spiralling beams. The Chimpositron features a dark green color with a red dish instead, but keeps the color of its blue beam.
The Chimp-o-Matic fires a continuous beam which slowly transforms enemies into a chimp over time, with the time it takes to transform an enemy being dependent on their health. It has no ammo, meaning it is unlimited. The effect the weapon has on transforming an enemy will refresh unless the beam is held on them until they are completely transformed, and can be easily interrupted if Ratchet is hit while firing. This makes it less useful against tougher enemies with greater health, as the player may not be able to hold the beam down on them long enough, and may be able to defeat them faster with other weapons.
The Chimpositron transforms enemies much faster than the Chimp-o-Matic. While this makes it a much more useful weapon against most types of enemies, it does not completely address its shortcomings, and the weapon is still more easily outclassed by more powerful weapons.
Behind the scenes
The Chimp-o-Matic/Chimpositron was one of the only transformation weapons in the series to work on a main boss (the other being the original Sheepinator). It had the power to turn Dr. Nefarious into an organic monkey when you battled him in A Crack in Time.
Unlike with all of the other weapons, the cartoon-like preview does not show Ratchet using it, but rather scientists trying to test it.