Credit to Ninja. When contacting another player to arrange a match, you can also decide what arena you want your characters to fight in. Feel free to suggest arenas either through post or PM. Tournaments will use randomized arenas.

Non-Specific Arenas:

-Coliseum Arena: The default arena, automatically used if no arena is specified. A simple, wide-open space with solid floors and walls. Always used in tournaments unless otherwise noted.

-BZPower Forums: You’ll start on the Index, but by no means does the fight have to stay there! Using the available warps you can jump to any Forum and hide in a crowd of members, opening topics to spill their contents in an avalanche of spam that may disrupt your opponent. If you clutter the Forums with too much spam or badly hurt too many members, Hapori Tohu will blast you with laser vision, so be wary!

-Seismic Showdown: A circular pit webbed with faults and tectonic masses that shift constantly, providing earthquakes of varying scales, geysers and magma explosions that sometimes occur on the borders. Ash and dust lightly rain down on the battlefield, but can collect into clouds and storms, sometimes blinding the duelists. When eruptions occur, flaming embers spew from the underworld, becoming hazardous to the surrounding area. There are small ponds and lakes that plume with steam from the heat, both from the pounding sun and the lava beneath. (Credit to Bulik)

Slizer Arenas:

-Storm Sector: A sector of the Slizer planet blanketed by a constant thunderstorm.

-Glacial Sector: A sector of the Slizer planet covered in snow and ice.

-Slizer Dome: Home of the Judge/Jet Slizer, at the north pole of the Slizer planet. Battles take place atop a tall building that you definitely don’t want to fall off of. Several computer terminals line the arena, and if you can find a working one you can program the tower’s defenses to treat the opponent as hostile…until the terminal runs out of power, of course.(Credit to Ninja)

RoboRiders Arenas:

-City-Realm: A RoboRider realm filled with dilapidated skyscrapers, abandoned highways, and swinging wrecking balls.

-Rock-Realm: A RoboRider realm made up of uneven terrain and plenty of rock formations to climb and hide behind.

-Swamp-Realm: Home of the Swamp RoboRider, in this cramped forest there are many vines hanging around and murky waters. There are also tales of a creature lurking in the mud, but those are just rumors…right? [spoiler alert: they're not] (Credit to Ninja)

-Core Matrix: The heart of the RoboRider world, a large, brightly-lit space with featureless floors and walls. Beware: traces of The Virus remain in the form of three-clawed tendrils that will sprout and attack you!

-Ice Realm: Similar to the Glacial sector, the Ice Realm is covered with ice and snow. Frequent blizzards batter the realm making visibility hard to see. (Credit to Snake)

Bionicle Arenas:

-Naho Bay: A body of water on Mata-Nui. If fighters fall off the lily pads, they will plunge into the water where Tarakavas and Takea sharks wait.

-Stalactite Village: The top of a stalactite planted in the ground of Karda Nui. You can hop to another nearby stalactite, but don’t fall—it’s a long way down.

-Charred Forest: A dark arena filled with dead trees. Not all of the Matoran traps have been disabled, and though they may not be able to hold you for long, they can cost you a crucial second. (Credit to Flaredrick)

-Atero Arena: Similar to the Coliseum Arena, but covered in sand and many pieces of jagged metal- old armor. You can use the metal to fight, potentially. (Credit to Ninja)

-Mangai Volcano: A platform of molten rock is suspended inside the volcano, which will erupt periodically. When it does, we recommend hiding in the tunnels within the walls of the volcano until the platform recreates itself. (Credit to Worldsoul)

-Mangaia: Makuta Teridax’s most well-known lair, a place of perpetual darkness. Manas can be heard scuttling around in the shadows, and the only light comes from the pools of Energized Protodermis in the center. If you fall in, you’ll slowly be burned alive, so I wouldn’t recommend trying to transform. You can hide behind some pillars, but if the foe destroys them they may unleash a Rahkshi.

-Mahri Nui: The match starts out in an air bubble in the sea below Voya Nui, but too much fighting will cause the bubble to pop, letting in the Pit Mutagen to turn you into water-breathers (but that’s the only effect). Being underwater weakens all attacks based off the Mind Stat, even if they wouldn't be weakened in real life. Fighters can swim, jump, and make use of the fact that they are underwater, raising their agility. (Credit to Canis)

-Iron Canyon: A canyon on Bara Magna with sheer rock walls. Rock falls can be triggered, a Skopio sleeps beneath the sand, and we have reports of Bone Hunters roaming in every now and again. (Credit to Vox)

-The Zone of Darkness: A pocket-dimension completely devoid of light, lacking all features besides a flat stone floor and occasional patches of Visorak webbing. Fighters must tread carefully and rely on their senses. The Kahgarak come and go, and they may be attracted to the sounds of a fight. Combatants are free to use their powers to produce light, but be careful not to draw the attention of the Zivon. (Credit to Keizah)

Hero Factory Arenas:

-Tanker Station 22: A Hero Factory fuel station in poor repair. Jets of flame and steam may erupt without warning, and shooting the fuel pods lying around will have explosive results.

-Quatros: A lush jungle planet populated by a variety of dangerous creatures.

-The Valiant: This Hero Factory ship has been infected by the brains! Due to it being in space, gravity is lower and it is cold, but watch out for the tubes- if you break them, you've unleashed a Brain and the fight gets a bit more complex for both sides! (Credit to Ninja)

-Training Sphere: This round battle ground is a giant sphere, able to resemble other arenas that you can use to your benifit. That is, if you find the controls first. Each fighter may change the arena the Sphere resembles once. Be wary of the HeroBall when a match begins, the arena splits in half and you've got to keep it in the air. Whichever side it hits the ground on is in for a nasty surprise, the likes of which depends upon the arena the Sphere is copying. (Credit to Zakaro)

-Hero Factory Villain Containment: This large, open area may not seem much at first, but that's only if you don't take into account the many cells lining the walls stacked on top of each other. Fighters will have to be careful to not damage the place too much, or villains will be roaming the arena as well, the amount depending on how much damage has been done to the cells in general. In addition, in the centre of the northern wall is Von Nebula's black hole staff. Be careful, fighting around it too much might unleash all of the villains, creating instant chaos for all fighters in the arena! An unfortunate fighter that gets too close during this might even get sucked into a black hole temporarily, where gravity is much lower than normal.

-Tansari VI: A power plant filled with electric generators. Fog obscures the arena, and lightning will strike randomly. (Credit to Flaredrick)