Omnitrix Access: Avalable but not used
Ditto (voiced by Rob Paulsen in a voice resembling that of Yakko from Animaniacs) is a Splixson (based on the word "split") from the Earth-like Planet Hathor (the first syllable of this name being similar to the word "half"). Ditto first appears in "Divided We Stand".
Ability
Ditto is a small, humanoid alien with the ability to clone himself without limit. Every clone operates independently, regardless of whether or not Ben wants them to, and each clone is indistinguishable from the others. Though the clones are autonomous, they share each other's pain, and the death of one clone will cause the death of the rest (as seen with Dr. Animo's Ditto-enhanced Stinkfly mutants) which negates the usefulness of making large numbers of clones. The child-size Ditto is also no stronger nor faster than his size and build suggests. In the preimere of alien force season 3, a ditto hologram was seen when ben was going through his aliens. Dwayne Mcduffle confirmed ben will not use ditto.
Weakness
If one of the clones get injured the rest will get injured, so if one of the clone dies the rest will.
Planet
The planet Hathor is home to a race called Splixsons who have not grown out of Mitosis (that is how they can divide without limit), but they don't fight or start wars (that was made clear in "Divided We Stand") they are more peaceful than other races, they are more like farmers or painters.