I do say I have create one character for Ben 10 Ultimate Alien! But I still draw it, so I didn't have anything to show yet. But the info about the character is:

Name: Rendall Yamato Tennyson
(Which he was Ben and Julie son from the future)
Age:17
Power: Anodite and magic spell(like his aunt Gwen)
Skill: Karate and alien techno knowledge

Name:Ben Tennyson
Powers:Aliens from omnitrix

I have to ask: I can only create ONE character?

First of all you have to make your favorite character form Ben 10 or from Ben 10 Alien Force or from Ben 10 Ultimate Alien. You don't make up one.

OK. I got it. Here it is:

Name: Ben Tennyson
Age: 16
Powers: Able to transform into various kinds of aliens with the Ultimatrix

There is another one.

Name: Ultimate Echo Echo
Species: Sonorosian
Home World: Sonorosia
Powers: Sonic discs, Super-fast flight, Soundwaves, Multiply sonic discs, Sonic forcefields, Sonic Doom.

This is the last one.

Ben Tennyson and Julie Yamamoto