Upgrade (voiced by Tara Strong) is the 9th Alien to appear on the series. Upgrade is a Galvanic Mechomorph (mecho- meaning machine and -morph meaning transform) of the planet Galvan B, a formerly uninhabited moon orbiting Galvan Prime. It was said to be born when self-replicating nanotechnology bonded with Galvan B's mineral molecules. It is supposedly the result of some Galvan scientists' dumping of chemicals with self-replicating nanotechnology onto that moon, probably by mistake.
It has the ability to reshape itself, as it can turn to some sort of liquid at will.Galvanic mechamorph's can also strech their limbs about 20 to 40 feet depending on it's age. Its internal nanotechnology allows for Upgrade's primary ability to merge with and 'possess' any technology within reach by spreading over it like liquid, enhancing it far beyond its original design.
The size of the device is inconsequential. While merged with a device, Upgrade controls it as he would his own body. Even without a machine at hand, Upgrade can reconfigure his form around his eye in order to fire a plasma beam from it. Upgrade is also capable of forming simple constructs from plasma, such as spikes.
Upgrade can also easily survive in the vacuum of space because it technically is not a living being and made up of no organic tissue. The Ben 10 Alien force alien, Goop, is believed to be a recycled form of Upgrade, having the ability to morph rather than merge with objects. But besides the color, Goop's shoulder spikes, Goop's UFO, and Goop's ability to make his slime acidic, the body shape is very similar. There is one episode in alien force (Pier Pressure) where Ben meets a galvanic mechamorph named Blorp.
In this episode, Blorp demonstrates the ability to reshape his fingers into tentacle-like appendages to push various buttons at the same time. This indicates that Galvanic mechamorph's can also reshape their bodies to an unlimited amount.
Upgrade's weakness is from its specialization: being technology-oriented, Upgrade cannot possess biological creatures (so Ben keeps his own voice when transformed), and sentient robots are harder for it to control.
It might also be possible that Upgrade may carry metal related weaknesses, like weakness against metal corrosive substances, as it seems to be composed of liquid metal-like substance, but this has never been shown in the series yet. Upgrade's body conducts electricity easily, making him vulnerable to it.
Unusually Ben keeps his human voice while transformed as Upgrade likely due to the Galvanic Mechomorph issue of not being able to bond to anything organic in nature. This either means Ben's transformation is not complete or the Omnitrix is built this way.
Ben 10: Ultimate Alien Edit
Upgrade returns in UA. He now looks exactly like Baz-El