All fights take place in one of the five different arenas, each one have it's own background music and hazards. As long as arena hazards is enabled in the gameplay menu, all the arenas save the Stadium will have an active hazard. Some of these hazards can be frustrating, annoying, or played upon to fight or counter the enemy.
In Multi-player games the most common is to disable hazards, or only play in Stadium because it doesn't have one. The hazard in Power Plant is bugged, and deals no damage, but interrupts air-juggle combos. Where the Fire Pit hazard is the only one that allows the player to manipulate the effect. Danger Room and Desert both have randomly appearing hazards.
The Stadium has no hazard. This makes it the most popular arena for Multi-Player games where people want a fair fight one-on-one.
The stone-spikes can be the most annoying hazard. The spikes appear semi-random, though they will usually appear in set patterns. They can sometimes be difficult to spot, because of the dark background and spikes, as well as robots in front obstructs view. The spikes make a sound when they appear, so you can listen for them. They deal little damage, but does a decent amount of stun damage.
Generally the spikes will appear where the players are standing, so moving about will usually help you avoid most spikes. This can also be used to fight off defensive players, as turtling up in the corner will almost guaranteed get them spiked. Ironically this also punishes corner blocks for the same reason, you're likely to jump into a spike.
Whenever a HAR is thrown or hit into the walls, they electrocute, stopping combos, dealing no damage.
This hazard actually deals no damage at all, not even stun damage. The only thing it does, is looking cool as you electrocute the enemy, and stops any air combos currently going.
This could possibly be used as a strategy in Multi-Player with a HAR like Flail that has little air combos, against a bot that depend on such.
Attack the fire hologram to place a fireball under your opponents feet.
This is the only interactive hazard in the game. If you damage the holo-fireball with kind of attack, a fireball spawns directly under the opponents feet, and shoots upward. This can create a small mini-game of hit the ball as players try to abuse it, but usually you will be better off concentrating on your normal attacks.
The Fireball does decent damage and stun, but is easy to dodge by just moving back or forth, or jumping away from it.
This Arena contains a secret in 1 Player Game, where you can go from this map to the two hidden opponents Fire & Ice. More about that in another area.
Dodge the attack jets that come at mostly random.
This hazard is very similar to the one in Danger Room. The jets comes at semi-random, but in preset patterns. They will typically attack where players are standing, so generally reward moving about. The Jet's machine guns deal very little damage, some stun damage, but mostly just attacks with several attacks that can hit-block your robot while being hit thus leaving you exposed.
This arena can be very annoying against the AI, as the jets can repeatedly interrupt your usual AI killing combos, and can make it difficult to setup that perfect combo. But it might just be one of the most interesting hazards in Multi-Player as it is a good dissengager, and its patterns are often wide enough to force both players to move.