Stalker

The Stalker is a robot presumably built by Oliver and commissioned by Will Harangue in which he recorded Ben's aliens' moves in a video game motion capture-type scamming. It's first and only appearance so far, was in the episode Video Games. It was beaten by Nanomech which was able to go inside The Stalker and ruin the robot circuits in which caused it to malfunction. It was then crushed by Way Big with the remains crashing in Will Harangue's car.

The Stalker's Protection against Ben's alien attacks:

 * It is not affected by Spidermonkey's webs
 * Has fire extinguishers for Swampfire's fire blasts and a liquid to kill his plants
 * Has retractable mirrors to deflect Jetray's nueroshock blasts
 * Extreme durability against physical and energy attacks
 * Has immense strength, allowing to easily overpower aliens like Humongousaur and Lodestar, as well as breaking Gwen's forcefields
 * Laser blasters
 * Has a cannon that can shoot strong adhesives to keep Cannonbolt in place
 * Can create enough heat to melt Big Chill's ice
 * Made of a non-ferrous metal so it wouldn't be affected by Lodestar's magnetism
 * Retractable claw/tentacle
 * Electric antennae/tazers
 * Missile blaster
 * Optional 360 degree vision
 * It can predict Ben's alien's techniques, like Humongousaur's fighting style, where Cannonbolt lands between bounces, etc.

Trivia

 * The Stalker does not have counter measures for Way Big, Nanomech, Alien X, or many of the then-unusable forms from the original series and Ben 10,000.
 * It seems to be a parody of the Omnidroid from The Incredibles.
 * The Stalker has Auto and Manual controls.