The Mechanical Maniacs gained this armour at the end of Series 2. In the series finale they faced the threat of Unicron. Using various elements they had collected to rebuild Gamma they rigged their base, the Technodrome, to launch at the monster planet and explode within him. Since their technology was greater than that of the 80's - when Unicron was first made - their plan succeeded in destroying him (for a time). As one of the elements was a Transmetal Driver the resulting shockwave hit the Mechs and gave them Transmetal armour.
The Transmetal Armour was based on various Megaman 3-related merchandise. There wasn't a full set of images for any given line (for example, at the time neither the full set of Nintendo Power nor Ariga designs were known), so there's a wide variety of sources for the various armours.
The general gist of this armour is that it gives the Mechs access to all the powers from all the games and media they've ever been in.
Needlegal possesses all of her original powers as well as all powers from her other incarnations. These being very few, it's mainly Superadventure Rockman. Needlegal's original look was based off the Playchoice-10 arcade art. In Series 5 she would alter her armour to be feminine.
Needle Cannon: Needlegal can spray the field with sharp needles
Needle Helmet: The spikes on her head can be propelled outward to skewer foes.
Needle Punch: Needlegal punches an opponent and her hand or cannon becomes a needle while doing so. (SA)
Needlegal is weak to the Gemini Laser.
Magnetman's armour is based off Nintendo Power's design (specifically, for their Megaman 2 GB coverage).
Magnet Missile: Magnetman can fire up to 3 Magnet Missiles at a time. They have limited homing capabilities.
Magnetic Attraction: Magnetman can draw foes close and damage them with his magnetic field.
Magnet Lift: In addition to drawing others to him, Magnetman can draw himself and cling to any metallic surface (that can be attracted by magnets).
Magnetic Shield: Magnet had a small device that hovers over him that can generate a shield using magnetism.
Magnet bomb: Magnetman can send a more powerful type of Missile at an enemy as well as the regular kind. These bombs can be highly resistant to attacks.
Magnet boulder: Magnet can lift a small boulder and throw it an enemy. These boulders tend to crumble when blown up, but their shards can still deal damage.
Magnetman is weak to the Spark Shot.
Geminiman's armour is based on the design found in Ariga's
Gemini Laser: A slow moving beam that can bounce off walls.
Arm Cannon: Geminiman can produce low-level buster shots on top of his laser.
Crystal Shield: Gemini can produce a strong shield.
Clones: This version of Geminiman can produce up to 6 copies to fight alongside him.
Fighting: Geminiman can deliver powerful punches and kicks.
Gemini Force: Not technically a part of the Transmetal Armour, but it was in use during Series 3 while he wore this armour. It was a present from the other Mechs for his birthday (they bought it using counterfeit money). It's a replica of the Seven Force without any transforming ability. Gemini mainly used it for flight. It was destroyed in the Series 3 finale.
Evil Lennon: During Series 3's the Ultimate duel Wily installed a control and enhancement chip in Geminiman. The effects of this are: attack absorption, control of the Gemini Laser, faster speed and reflexes, charging, and the ability to cast "magic" in his human form (which, in reality, were just glorified Robot Master attacks accessible in this alternate form).
Geminiman is weak to the Search Snakes and heat-based weaponry.
HardmanEditHardman's armour is based off Nintendo Power (specifically their coverage of MM2 GB).
The Hard Knuckle: a powerful projectile that consists of Hardman shooting his lower arms at his opponent. They have slight homing capabilities and are able to return back and quickly reattach themselves. Naturally he can only shoot two at any given time.
Hard Press: Hardman leaps high into the air. Then he stops, aims downward (in midair, mind you) and then propels himself downward. The force is enough to shake the room and stop enemies in their tracks.
Double Hard Knuckle: Hardman holds both hands together and shoots both Knuckles off at the same time. This is more powerful than his standard attack, but it loses it's homing abilities.
Spiked Knuckle: Spikes are added to his arm for a nastier punch.
Mace Launcher: Hardman can launch a large, spiked ball from his chest at an enemy.
Hardman is weak against Magnet Missiles and has also demonstrated a weakness to sound-based weapons (thanks to the cavity in his chest and other hollow areas).
TopmanEditTopman's armour is based off Nintendo Power (specifically their coverage of MM2 GB).
Top Spin: Topman is capable of moving at extremely high speeds. When he spins he can cause damage when he crashes into anyone. The Top Spin can also deflect attacks, or at least minimize damage.
Super Top Spin: Topman can spin even faster to look almost like a top himself. Getting his with this causes even more damage. This can also deflect attacks.
Top Toss: Topman can toss tops at enemies. In the game this comes form his head, in this armour it's done Beyblade style: with a launcher or just out of thin air.
Wind Shear: Using high speed Topman can cut through the air to create up to six cutting winds (up to three with each arm).
Wind Gust: Top can spin fast enough to send a gust of wind shooting at an enemy from a distance.
Topman is weak to Hard Knuckle.
SnakemanEditSnakeman's armour was based off the Ruby Spears cartoon.
Search Snake: These are several small snakes that can crawl along the walls and go around to seek and destroy their target.
Snake Dive: Snakeman can burrow through soil to emerge and attack from anywhere. Snakeman is vulnerable to the Needle Cannon.
Sparkman / Spark ChanEdit
Spark's design was based off the Tiger handheld game. When Classi took over the roll her face and hair was shown.
Spark Shock: Spark can produce a flurry of sparks which can either damage or immobilize a target.
Charged Spark Shot: Spark can charge her weapon and release a large, powerful charged shot.
Lightning Bolt: Spark can shoot a lightening bolt into the air and have it crash down on a stationary enemy in a singular, powerful attack.
Spark Swipe: Using energized blades, Spark can take either a single or twin swipes at an enemy. Not only can the sharp spires hurt, but they also give the foe a shock. Quick, short slices are also possible.
Thunder Swipe: With a swipe from charged electrodes, Spark can send tin paris of electric currents at an enemy form a distance.
Spark is vulnerable to the Shadow Blade.
Shadowman's armour was based off Argia's mangas.
Shadowblade: A large ninja star that travels a distance and then returns back to Shadowman. This is due to it being made of an alien material. Moreover it's coated in a substance that damages mecha.
Speed: Shadowman is one of the quickest Robot Masters.
Sliding: Shadowman can use Megaman's sliding ability. Cling: Shadowman can cling to walls or the roof at times.
Tacks: Shadowman can throw tacks on the ground to deal out minor damage and as a general inconvenience.
Log: Shadowman can turn into an invulnerable log (probably not made of real wood).
Frog summon: Shadow can summon a giant frog which leaps high, has a "tongue lash" attack, and breathes fire.
Ninia Frog summon: Shadow can summon smaller frogs as well.
Hologram: Shadow can create up to three holograms of himself (sometimes up to six). These holograms are distractions only and have no true attacking ability.
Arm Cannon: Shadowman is equipped with a standard Arm Cannon. This is a highly secret attack and Shadowman reserves it only for use for an emergency. It's only a standard Arm Cannon; it's use would be purely strategic.
Disappear: Shadowman can disappear in a puff of smoke and reappear a short distance away.
Sword: Shadowman carries a standard sword.
Shadowman is vulnerable to the Top Spin.
While a wide variety of powers are listed here, the truth is that lack of video kept this armour series at a bare minimum in terms of power levels with sprites and descriptions only being partially helpful in figuring out attacks used in games like Superadvanture Rockman. In the end authors tended to pay special attention to the powers of their own characters more than that of others (especially Gauntlet).