it is a game that you mix up 2 aliens in Ben's watch and see what it makes
ben got his aliens from his watch
You type in the DNA codes for the aliens and mix them to make a new alien.
Ben 10 has more than ten aliens while protecting the earth.
are you kidding i AM Ben ten
ben 10 aliens unleashed or ben 10 evolution
10
It is assumed he doesn't, as the new aliens are "fusions" of the aliens from the original series.
The Omnitrix (the watch-like device he uses to transform into an alien) has 10 aliens at time. But it happened that Ben managed to "unlock" more aliens by collecting their DNA.
A list all the aliens ben has
10
None of them has all the aliens