Buster

A Buster (バスター) is a term for a high tech firearm that shoots energy bullets. It is mainly equipped by combat robots and Reploids, although it has been wielded by NetNavis, humans and Carbons in certain time periods.

Characteristics
The term Buster is mainly used for convertible arm cannons, but it is also used for a few handheld weapons with similar characteristics. They are compatible with several power sources, such as solar, atomic and even Bassnium. Busters can be customized to function in different ways: some can charge energy to fire a bigger and stronger shot, while others can have a rapid-fire function.

The Busters from most main characters in the franchise are very practical weapons due to their adaptability, decent rate of fire (though only rapid-fire variants can fire more than a few shots at a time) and virtually unlimited ammo. Arm-mounted variants can usually change the barrel into a hand and back (although some exceptions exist). It is possible to combine buster technology with the Weapon Copy System, or in case of handheld variants, install elemental chips to change the properties of their shots.

However, the buster's qualities do not make it an unbeatable weapon: certain weapons, such as the Mirror Buster and the Ring Boomerang were designed to counter Buster weaponry. And certain types of robots are outright impervious to buster fire, like the helmet of Mets and the Stardroids.

Busters in the Games
Note that due to the large amount of characters with arm cannons, only major Busters are listed.

Mega Man (series)

 * Mega Buster: Mega Man's weapon, powered by solar energy. It was upgraded to the New Mega Buster, and later to the Super Mega Buster. Compatible with the Weapon Copy System.
 * Proto Buster: Proto Man's weapon, powered by atomic energy. More powerful than the Mega Buster, but has greater energy consumption. Compatible with the Weapon Copy System.
 * Bass Buster: Bass's weapon, powered by Bassnium. It was eventually modified with a rapid-fire function. Compatible with the Weapon Copy System.

Mega Man X (series)

 * X-Buster: Mega Man X's weapon, also known as Mega Buster Mk. 17. It can be further upgraded with armor parts. Compatible with the Variable Weapon System.
 * Zero Buster / Z-Buster: One of Zero's weapons. Very powerful, although its use has diminished in favor of the Z-Saber. Although it appears to lack a Variable Weapon System, the Z-Buster technology can be used to enhance the X-Buster.

Mega Man Zero (series)

 * Buster Shot: An old handheld model equipped by the Resistance and borrowed by Zero, who found ways to enhance it by equipping the Z Saber as a magazine, and combining it with his EX Skills. It can also be equipped with the Thunder Chip, Ice Chip or Flame Chip.

Mega Man ZX (series)

 * X Buster: The Mega Man Model X's standard weapon.
 * ZX Buster: Produced by the combined abilities of Model X and Model Z, Model ZX, the ZX Buster fuses the X Buster and the Z Saber into a single weapon.
 * Buster Shot: A standard-issue handheld model wielded by the Hunter's Guild and borrowed by Grey. It is compatible with Biometal Model A.

Mega Man Legends (series)

 * Mega Buster: Mega Man Volnutt's weapon. It can be outfitted with a variety of enhancements.
 * Steel Buster (こうてつバスター): The buster of Steel Prince, a fictional character in the series. Outside Japan it was renamed as Ken's "Dragon Punch".

Mega Man Battle Network (series)

 * Mega Buster: MegaMan.EXE's weapon. It can transform for the use of Battle Chips.

Mega Man Star Force (series)

 * MegaBuster: The primary weapon of Mega Man, the EM Wave Change of Geo Stelar and Omega-Xis.

Marvel vs. Capcom

 * Roll Buster: A red cannon that Roll can slip over her arm. Compatible with Weapon Change.

Dead Rising

 * Mega Buster (fake): A toy version of the Mega Buster that fires ping-pong balls.
 * Real Mega Buster: The real article fires powerful energy blasts. Unlocked with the "Zombie Genocide" achievement.

Street Fighter X Tekken

 * Mega Buster: A pistol used by Mega Man. It can fire a Charge Shot called "Mega Cannon" as a special move.

Tatsunoko vs. Capcom: Ultimate All-Stars

 * The Real Mega Buster: A Hyper Combo which consists of Frank West equipping the weapon to fire a massive energy beam.

Rockman X Mega Mission (series)

 * Clear Buster: A mutation of the X-Buster caused by Limited. As the mutation progresses, the weapon changes into the Clear High Buster. It has massive power, but causes X to struggle against the Limited influence.
 * RX Buster: A Limited copy of the X-Buster wielded by Return X. Extremely powerful.
 * Neo Buster: A new weapon created by Zero as a result of remodeling the Z-Buster with pieces of the X-Buster.

Notes and Trivia

 * The original Mega Man can change both arms into the Mega Buster, but avoids using them simultaneously due to the danger of the output overheating his systems. Mega Man X and Zero have also used both arms (albeit interchangeably).
 * Arm mounted Busters seem to drain the robot's own energy reserves: Proto Man, for example, is severely weakened after using the Proto Strike. This is less of an issue for Mega Man since his helmet has a solar panel to gather energy. Bass reportedly has an infinite Bassnium supply.
 * Some special weapons also have "Buster" in their name: Grab Buster, Mirror Buster, Active Buster, Buster Cannon, Machine Buster, Powered Buster and Spread Buster.
 * Buster Shot (バスターショット) is the name of Zero's handheld weapon in the Mega Man Zero series. The name was also used for the three types of Mega Busters in trailers from Mega Man Universe.