Mono Beetle

The  is a robot deployed by the military organization Guardian Units of Nations. It is the most basic model in the Beetle series and its design serve as the template for all the other robots in the Beetle series. It appears as an enemy in Sonic Adventure 2, Sonic Adventure 2: Battle, Shadow the Hedgehog and Sonic Generations.

As the Mono Beetles serve as little more than surveillance drones, presumably to support the security functions of G.U.N's bases, they are rather harmless and can occasionally be used as "steps" for Sonic and Shadow to cross by using Homing Attack.

Appearance
In Sonic Adventure 2, Sonic Adventure 2: Battle and Sonic Generations, the Mono Beetles basic structure resembles grey-colored balls with a blue outline. On the top of the Mono Beetles, they have a blue cap with a red stripe, with G.U.N.'s symbol and the number "05" on it. Also, right below their cap, from the front edge of their main body to behind their back, the Mono Beetles have circular dishes, with red and blue stripes on the side, attached. The Mono Beetles are also equipped with security cameras, which resemble yellow lenses, in the front.

In Shadow the Hedgehog, the Mono Beetles are given a slightly different design which make them closely resemble Bomb Wings. In this game, rather of their usually blue colors, the Mono Beetles are given a green color instead. Also, their dish attachments are made thicker, resembling jet engines and have a pair of small wings attached to the sides.

Attack Pattern
The Mono Beetle has no method of attack, unlike most other robots in the Beetle series, and will only hover around in the air. When a Mono Beetle espies the player, its "eye" will light up and it will bob up and down excitedly. Sometimes, a Gun Beetle can be invisible to the player can and appear out of nowhere when a character comes near it.

Sonic Adventure 2 and Sonic Adventure 2: Battle
The Mono Beetle first appeared in Sonic Adventure 2 and its remake Sonic Adventure 2: Battle. They are some of the games' most common enemies and are found in nearly all the games' stages:

Shadow the Hedgehog
The Mono Beetles made their first return in Shadow the Hedgehog. In this game, they are a common enemy in the stages where G.U.N.'s forces can be found, such as Westopolis.

Sonic Generations
The Mono Beetles reappeared once more in Sonic Generations, with their behavior and appearance being just as they were in their original game. They appeared in both acts for Radical Highway on the 3DS version and in both acts for City Escape on the console version.

Merchandise
This robot was included as a bonus figure with a Shadow figure from Jazwares for the "Sonic through Time" line. However, it incorrectly says "2000" instead of "2001", which is the correct year Sonic Adventure 2 was released, on the box.

As of 2012, the date hasn't been changed despite the fact that Jazwares added a new sticker to cover the outdated 20th Anniversary logo.

Trivia

 * According to Kazuyuki Hoshino, the Beetle got its inspiration from San Francisco Parking Attendant vehicles. They were put in the game as a way of getting revenge for all the parking tickets he and Takashi Iizuka got during the development of Sonic Adventure 2.