To enter the arena in Genealogy of the Holy War you must enter a castle and then select the arena from there. A unit can only successfully defeat an enemy in the arena up to seven times in a chapter, however if a character is defeated in the arena they are left with one hit point. Unlike arenas in the rest of the series, the enemies you fight are all preset, so all the characters will fight the same enemies. (which means you cannot do an "Arena Gauntlet") although having preset enemies does make it easier.
Arenas also appear in Shadow Dragon. However, unlike the arenas in the Game Boy Advance games, the arenas in Shadow Dragon allow an option to use the arena again at the same turn once winning, thus allowing players to use the arena multiple times in one turn. However, this option can be extremely risky as the player has not had the chance to heal the unit from the previous fight. The training grounds can be accessed during battle preparations in Shin Monshō no Nazo ~Hikari to Kage no Eiyū~ act very similar to arenas, but no money is won, the character uses his/her own weapons, is healed between rounds and their stat gains when leveling are different, namely (sum of growths/100) stats grow with a chance of one more stat growing. This allows the player to use training grounds to maximise stats much like Bonus Experience from Radiant Dawn.
Somewhat like 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. If your unit falls, or you press the B Button to back out, you lose your wager.
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 you have pressed the B Button, the battle will end prematurely and you will lose your wager if one was made. Use this option to get your unit out if they are close to their death.
Fire Emblem FatesEdit
Arena is available after being built in My Castle in Fire Emblem Fates, but in this game it cannot be used to get 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.
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.
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 he or she can. Then the abuser can repeat the process.
Since you get money from frequently winning at arenas, and that Arena weapons are not the weapons you are equipped with, one can keep doing this until all units are level 20 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.
An "Arena Gauntlet" is when the player constantly uses the arena without healing and not using some form of "random number generator" abuse. The option that allow players to go into another match in Shadow Dragon makes it easier to do an "Arena Gauntlet" in one 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. But 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 easy using emulators, 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 do something similar to save states on the EZ Flash IV flash cart, by suspending the game, resetting the GBA, and reloading the game. If your unit dies, restart the GBA and press L to skip the saving process.
- In the GBA games 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.
- In Fire Emblem: 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 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 Ankoku Ryū to Hikari no Tsurugi; Thracia 776 used the first player map theme from Monshō no Nazo; 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: Rekka no Ken, 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.)