First Appearance: "Mach GoGoGo," a manga feature of the 1958 Shönen Book, later reissued in book form.
Other Appearances: Mach GoGoGo (anime, Tatsunoko Productions, April 1967 to March 1968), better known in the US as Speed Racer, where it was released and aired by Trans-Lux in syndication starting in the fall of 1967. Also, of course, the American live-action movie, as well as a number of different comic books in Japan, the US, and other countries.
Merchandising: Chim Chim has been made as an action figure, and possibly merchandised in other ways in Japan. I don't know if he appeared in any of the Speed Racer video games.
Biography: In the first episode of Speed Racer, Chim Chim is already present as Speed's younger brother Spritle's pet, so we don't really know how Spritle first acquired him. Chim Chim is really treated as more a member of the Racer family than as a simple pet; indeed, he seems to operate more as Spritle's twin brother in many ways, including wearing an almost identical outfit to his human "brother." Chim Chim is a very intelligent chimp, who understands Spritle and other characters completely, and is also a very capable foe of evil-doers! There are several scenes in which the duo defend themselves successfully against an array of criminals, usually utilizing slingshots and whatever ammunition is handy. The duo are best known, however, for sneaking into the trunk of the Mach 5, usually when explicitly told by Pops (Speed and Spritle's father) not to go with Speed somewhere. Another characteristic of both is their love for candy -- like Scooby-Doo with his Scooby Snacks, the two would do anything for candy!
Powers: As noted above, Chim Chim is a very intelligent chimpanzee. He not only understands English, he is capable of following detailed instructions. Through the use of mime, he's also able to make himself understood more often than not, especially when Spritle is in trouble and needs help from Speed.
Miscellaneous: I was a huge fan of Speed Racer when I was growing up, and continue to be to this day. Chim Chim may have been the first ape that I was exposed to (with the possible exceptions of Bingo from The Banana Splits, the animated King Kong, or Blip from Space Ghost). I'm amazed that there hasn't been a plush figure of him produced for the American market!