Ultimate bigchill :
he can be invisible
he can pass through walls
he can breathe cie flames
Alien-X
Four arms is Ben's strongest alien ever
Alien X.
The strongest creature is Alien X.
he is humongousaur
4 arms.
Way Big
4 arms is the best because hese the strongest alien
Humungousaur,Way Big and XLR8 oh i fergot Alien X! No, Ultimate Ben is the strongest.
ben 10 rocks.he is stronger than naruto and goku.William is the coolest and strongest guy ever.
in Ben 10 alien swam Ben is 15 because it is the the category of Ben 10 Alien Force and in Alien Force he is 15
there is no weakest alien in Ben 10