Design and inspiration
Both its name and appearance are based on astromech droid R2-D2 a recurrent character in the science fiction franchise Star Wars and part of a mostly-comedic duo along protocol droid C-3PO (expanded into a trio with new arrival BB-8 in The Force Awakens). Despite possessing no apparent significance in the Gex universe, the "R2" prefix of its named is used to describe a specific model series in its source material, collectively known as "R2 units", whereas the code after the hyphen serves as the individual droid's designation. As implied by its name (and in a notable departure from its inspiration's helpful disposition), the R2-Beat-U's belligerent nature makes it yet another member of the longstanding "evil (or killer) robot" trope that has dominated popular culture for a century.
Several characteristics of its inspiration are warped in the design of these enemies. Like R2-D2, the R2-Beat-U units are divided into a main body and a gyratory top dome that serves as its "head". However, whereas the original droid possessed a cylindrical body, the enemy's body is altered to a trapezoid shape, being narrower towards the bottom of its torso. R2-D2's lone red-colored and circular sensor is altered into two symmetric eyes leading to a menacing stare. R2-Beat-U's preserve the blue and white color scheme, although color variations appear to be decorative instead of demarcating the droid's different components. The enemy unit also features a large compartment door, reminiscent of those in the R2-D2. R2-Beat-Us replace the R2-series retractable center thread with a more simple wheel and axle setup in a solid black frame, they also lose their namesake's stabilizing arms and additional threads, forcing the unit to jump in a fashion similar to an unicycle, although this doesn't affect their mobility.
Behavior and strategy
While not paying attention to Gex, R2-Beat-U units rotate their top dome from side to side as if scouting the terrain for enemies. Once approached they will begin maneuvering for space around Gex, executing frontflips throughout the area before pausing and reveal a blaster held in a retractable arm located in his chest compartment. This weapon is reminiscent in shape of a submachine gun and besides a blue midsection composed by four blue squares it is gray and black, oddly it also features what appears to be a clip and recoils when fired despite being an energy weapon (and even making a "charging" sound that reflects this nature when shooting). When R2-Beat-U units use this blaster it produces three slow-moving whitish blue-green plasma bolts before retracting it back into its body, opening a time window to attack it by evading the projectiles. When cornered and attacked they will hop around while the top of its dome flashes red and sit down (by retracting its wheel and turning "off", as indicated by it's eyes) then they will self-destruct. The resulting explosion will hurt Gex if he's within its radio. During the hopping stage of this sequence, the R2-Beat-U can be deflected with a tail whip, creating a safe distance.
R2-Beat-U's are actually one of two direct references made to R2-D2 by name in the Rocket Channel stages, the other being one of Gex's random quips, "There's a gecko on my tail, R2, see what you can do with it!" which is a paraphrased reference to one of Luke Skywalker's lines in Episode IV: A New Hope: "I'm hit, but not bad. R2, see what you can do with it. Hang on back there."