The Arena (闘技場, Tōgi-ba, also known as Colosseum) is a building that first appears in Fire Emblem: Shadow Dragon and the Blade of Light, changes drastically in Fire Emblem: Genealogy of the Holy War and reverts to a form similar to that of its original appearance in Fire Emblem: Thracia 776. Arenas do not appear in Fire Emblem: Path of Radiance or Fire Emblem: Radiant Dawn, but return to the series in Fire Emblem: Shadow Dragon; in all, they appear in 11 games. However, they are once again absent in Fire Emblem Awakening. Arenas are mainly used to train your characters and gain money in the process.
As in the Link Arena, only classes that can fight may enter the arena. When you enter a unit into the arena (except for in Genealogy of the Holy War), you are given the option to wager an amount of gold. If you accept, your unit will do battle with an opponent. If your unit wins, you win even money on your wager, and gain some experience.
The battle that takes place in an Arena works the same way as a battle in the field, except that instead of stopping once each unit has made their attacks, this process repeats until one unit is defeated, you retreat, or both units find themselves unable to damage the other. After each repetition, if the B Button is pressed, the battle will end prematurely and you will lose your wager if one was made. This option can be used to pull units out if they are close to death.
To enter the arena in Genealogy of the Holy War, units must enter a castle and then select the arena option from there. A unit can only successfully defeat enemies in the arena up to seven times in a single chapter, and if a character is defeated in the arena they are left with one hit point. Unlike arenas in the rest of the series, the types of opponents faced are preset, so each character will fight their own line of enemies (meaning you cannot do an "Arena Gauntlet"), although having preset enemies makes the process significantly easier and more predictable.
Arenas also appear in Shadow Dragon. However, unlike in the Game Boy Advance games, the arenas in Shadow Dragon have an option to fight in the arena again in the same turn after winning, allowing players to use the arena multiple times in one turn. This option can be extremely risky as the player is not given the chance to heal the unit from the previous fight. The training grounds that can be accessed during battle preparations in New Mystery of the Emblem act similarly to arenas, the differences being that no money is won, the character uses his/her own weapons, is healed between rounds, and their stat gains when leveling up are different, namely (sum of growths/100) stats grow with a chance of one more stat increasing. This allows the player to use training grounds to maximize each unit’s stats much like Bonus Experience from Radiant Dawn.
Fire Emblem Fates
Arena is available after being built in My Castle in Fire Emblem Fates, but in this game it cannot be used to gain money or experience - rather it follows a completely different set of mechanics. Players can gamble one their resources (miscellaneous resources such as foodstuffs and ores) in a set quantity of one.
Every playable character, excluding logbook units, are capable of participating in the arena during the morning, afternoon, evening, and nighttime hours, provided that they are in a class that is capable of fighting. The Arena Shield, an accessory bought from the Accessory Shop (or gifted by visiting players), will have their user participate in the Arena more often. This effect does not apply to logbook units.
Upon entering the Arena, a random character will be in the Arena, waiting to fight. If that character does not have any supports, or the player visits another player's arena, fights will start in a 1v1 format. If the character does have any supports, the highest support (or first one in their "bonds" if that unit has multiple same Support levels with other units), that character will also arrive and help out in the battle, and a 2v2 format is put in instead, with both sides utilizing Attack Stance.
The player participates in the Arena by gambling a resource they have. The opponent(s) your units face are randomly generated to their strength; for example, an early Jakob or Felicia will initially fight unpromoted units, but as they get stronger, the enemy will also get stronger and be promoted instead. The generated enemies do not have any skills, but they should not be underestimated anyways as the game can produce unusually powerful units (such as Onmyojis with very high magic and able to double your fastest units), or produce durable units that have high strength and defense, but not much damage. All units, player and enemy, are given Iron weapons of their primary weapon style, unless all of their weapon types are E rank, forcing them to use Bronze weapons instead.
The generated enemies will also depend on your path; on Birthright, you will only get Hoshidan opponents, while in Conquest, only Nohrian opponents appear. Revelation gives both Hoshidan and Nohrian opponents.
If you win the fight, your gambled resource is doubled. Losing forfeits your gambled resource. Higher leveled Arenas can net more consecutive fights; a level 2 Arena allows for two fights in a row, and a level 3 Arena allows for three. The Arena is one of the few buildings in Fates that cannot be destroyed in their castle.
Fire Emblem Warriors
In this game, Arena is a form of battle style within History Mode, with a max deployment limit of 2 units, often necessitating a Pair Up. In this form of battle, time is not a gradable thing, allowing players to fight as long as they can.
Battles here are usually a matter of 3 opponents against the two playable units, with the later waves of enemies often bringing in 1 or even 2 backup units when a opposing Hero unit is in critical health. When players with significantly overleveled units replay earlier Arena battles, they cannot KO anyone until the announcement of the wave is announced, and they cannot KO a enemy Hero unit until after their call for help is answered.
The player can forfeit this battle scenario by running out of the opened Arena doors, which close when the game registers that the player has engaged in combat.
Some people have taken to the hobby of "Arena Abuse", one of the most commonly used Sources of Infinite Experience. It's done by sending units into the arena constantly until they are weak, so that they can get healed by staff wielders. If the player did not bring a user who can use staves, then a Vulnerary will work, but not as well. The player constantly heals the fighter up until the Heal staff breaks. Usually, all levels with an Arena have a Shop on the same map. The player takes advantage of this and buys as many Heal (or Mend, if Heal staves are not sold there) staves as they can. Then the abuser can repeat the process.
Since you get money from frequently winning at arenas, and because arena weapons are separate from what the unit has equipped, players can keep doing this until all desired units have reached their maximum level and the abuser has enormous amounts of gold earned from the arenas. The process of arena abusing, without losing any units, is rather difficult and tedious outside of illegitimate exploits.
An "Arena Gauntlet" is when the player constantly uses the arena without healing and does not use any form of "random number generator" abuse. The option that allows players to go continue on to another match in Shadow Dragon makes it easier to do an "Arena Gauntlet" in a single turn, somewhat redeeming turncount, although this can be risky.
- In Fire Emblem: Mystery of the Emblem, arena abuse is slightly more risky at times as Manaketes of all kinds except Earth Dragons can appear in the arena. Despite this, the player cannot bring their own Manakete in.
- Mystery of the Emblem also has a set list of opponents depending on class. For example, Fighters will never face any type of dragon in the arena. Curiously, Soldiers have a list of classes to face in the arena despite being unplayable.
- Arena Abusing is made easy using emulation, since many of them can create "save states" that overrides the save mechanics of many Fire Emblem games. If things go bad, players can load save states to recover their advantageous data. It is also possible to accomplish this on the “EZ Flash IV” flash Game Boy Advance cartridge, by suspending the game, resetting the console, and then reloading the game. If your unit dies, you can again reset the console and press L to skip the saving process.
- In the GBA games where you can enter the arena and pay for a match, at the screen where it shows what class you are fighting, if it is not in your favor (i.e. Fighter against a Myrmidon) you can soft reset the game, and when you continue you will be at a screen outside of the arena, allowing you to reenter until you are presented with your desired match.
- In Fire Emblem: The Binding Blade, there happens to be a very rare glitch where a character will fight a Brigand with an Iron Bow  or a Warrior with a Fire tome. The screen will fade black and health bars of the duelists appear as if the player turned the animations off. In most cases, the battle will have one of the duelists take damage in one round and the battle ends abruptly, leaving the player with no reward at the end.
- In The Binding Blade and Sacred Stones, characters will use their highest ranked weapon; this can be detrimental if you intend to specialize a promoted unit in a weapon they do not start with (Ex. a Falcon Knight you want with an S rank in swords.)
- Likewise, the arena entrance music will often contain a remix of a song from an earlier game: Genealogy of the Holy War uses the player map theme from Shadow Dragon and the Blade of Light; Thracia 776 used the first player map theme from Mystery Of The Emblem; The Sacred Stones uses the prologue theme from Genealogy of the Holy War, and Shadow Dragon uses Clash, the battle theme from Path of Radiance. While talking to the fightmonger, Follow Me from The Sacred Stones plays.
- Enemies gain Difficulty Modifications in the Arenas, based on how much money you wager, even breaking class caps.
- In Fire Emblem: The Blazing Blade, due to a glitch, if a Dancer or Bard uses a ring on a character and the character is rescued prior to the end of the player's turn the bonuses will still be in effect. If a character positions a unit with high constitution to a space one space south of the arena and one space east or west of the arena, then a unit (like a Falcoknight) can rescue the character after that character has used the arena. On the following turn a unit takes the character with the modified stats from the flier and drops them on the same turn; a healer can heal the unit if they took damage, and then the Dancer/Bard can use Dance/Play on the character, giving them another turn and allowing them to use the arena with their stats modified until the player does not rescue the character again. This happens with all status effects. (This is actually a glitch with status effects in general, a unit will not, for instance, take damage from being poisoned if rescued nor will the turn counter for sleep decrease.)