Tonto is an Omnitrix guardian from the world Omnimation.
Tonto, though is caring and protective, is kind of missing a few brain cells. The Omnitrix on his wrist is a prototype of his master's Omnitrix, so it's missing the DNA of the Galvan (Greymatter.) Tonto also sometimes argues with his master, because for a fact, they don't agree on anything, unless it involves defeating a bad guy, or Tonto's little sister Kayla. Sometimes, Tonto just doesn't like Omnitrix the First as much as Omni doesn't like him, proof when one time a wishing rock got into Tonto's hand (after it was found by Omnitrix1 and Thomas) and when Omni gave Tonto a bunch of chores to do, he wished Omni was never born, 'thus making Omni vanish right in front of him, and no one even had any recollection that there ever was an "Omnitrix the First." But for some strange reason, Omni and Tonto trust each other with their lives, even if the feel like killing the other most of the time, which is almost all the time with Omni sense he has built up anger that he stored up from taking insults from kids that just want to get him angry for laughs.
In an alternate universe, Tonto actually is a pixie king, and instead of having the ability to transform into 1,000,902 aliens, they're all his minions.
Tonto has been changed twice. The first was where he and Omni went into a universe where the Omnitrix didn't exist, but Omni still wanted to protect, thus renaming himself Omnitrix2, or Omnitrix the Second, so niether of them had an Omnitrix. The second time was when he and Omni were approached to become Ultamatrix guardians, a higher ranking version of the Omnitrix guardians, but also secretive (the Ultamatrix is what Ben wears in the new Ben 10: Evolution series, I think. Wikipedia keeps changing.) Omnitrix eventually became Omnitrix4, or Omnitrix the Fourth (if I ever get a youtube account then this is what I'm calling myself) Tonto also became a little smarter, but not by much. Tonto may be a little stupid, but you wouldn't want anyone else there to back you up.
Tonto in the KrspaceT dimmension has a interesting case. His luck is magnified decreasingly when around his master, but turns the exact opposite around his girlfriend, the whitch Wendy. He also is old friends with Chowder. In the future he has a daughter named Jen with Wendy, and has become rich, owning the IWHL, Mr. Smoothie, Jurassic Park and Ingen, the Malt shops, the Galleria Mall, has a share in the Dexlabs corportation and has hundreds of minions of the fairy jedi squirel and Kuriboh variety. See Tonto's future minions