The Omnitrix's tendency to give Ben the wrong alien started out as only occasional, only to get worse over the course of the Original Series and even worse by the time of Omniverse, where it ends up becoming a surprise when he actually gets the alien he wants.This is why he wore sunglasses when he infiltrated the Incurseans as Bullfrag. Eyes Are Mental: Though this wasn't the case in the original series, from Alien Force onwards, all of Ben's transformations have green eyes, just like Ben himself.The Omnitrix has a fail-safe that will turn him into whatever form is necessary to avoid his death. This is explicitly confirmed by Ben in the Omniverse finale. Empathic Weapon: Strongly hinted the Omnitrix is never specifically stated to possess a will of its own, but it does act like it had one occasionally.Emerald Power: The Omnitrix's signature color is green, which also happens to be the favorite color of both Azmuth and Ben.Likewise, the original series depicted it as growing with its wearer (the first seen Ben 10,000's was bulkier than both those of Ben 10 and Ken 10), a detail which none of the later series incorporated.
In the movie, the dial has a column of hardware attached when Azmuth removes it. In "Back With A Vengeance", it unhinges more measuredly but from the back. It unhinges from the front like a blob of slime, lacks the green/black circuitry, and the dial/faceplate is an isolated piece of hardware. Early Installment Weirdness: When Ben first finds it, it behaves like a piece of Organic Technology prone to Body Horror.This means that Ben and any other user has to learn every individual power and weakness of every alien on the fly, and how the device works in the first place.
Though by the last season of Alien Force this is no longer true, as Ben knows exactly how to remove the thing whenever he wants. This prevents villains from simply taking it from him. Clingy MacGuffin: The thing is stuck on Ben's wrist.Most commonly in the center of the chest, but it does vary for some. Chest Insignia: The Omnitrix's symbol will appear somewhere on the body of every alien it transforms its wearer into.This frequently causes him to take the wrong transformation, turn back to normal at the wrong time, or merely make mistakes. Black Box: Ben has no idea how the Omnitrix works at the beginning of the story the best he can do is turning and pushing the dial.
Female Tetramands are stronger than males, and Ben as Fourarms faced off against the Warrior Princess Looma, Warlord Gar's Greatest Warrior and not only matched her in strength, but defeated her in combat.
The only other Incursean to look significantly different is Attea.