The Arena
The Arena originally appeared in Dragon Warrior II in Osterfair Castle. Here you had to battle a Saber Lion in order to get the Moon Crest. It has since appeared in some form in all other Dragon Warrior/Quest games excluding VII.
Dragon Warrior/Quest III
In the third installment of the series, The Arena becomes a place where spectators come to watch monsters battle and bet on the out come. The Castle of Romaly, Isis, Samanao, and Cantlin all have a monster Arena in their casino.
Dragon Warrior/Quest IV
The Arena is available to you in Chapter 2 Princess Alena's Quest in two forms. First there is The Arena in the casino, then there is The Arena behind Endor Castle where Alena must prove her strength. This is the second time in the series that you actually fight in The Arena. In Chapter 4 there is another monster Arena in the casino in Haville.
Dragon Quest V
Oracleberry is the location of the only casino in the game and hence is the only place to find The Arena. This Arena functions just like all the other casino Arena's.
Dragon Quest VI
In Dragon Quest VI things get a little different. During your travels you will come across something called the Slime Arena, in which you will be able to have the slimes you have caught using you Beastmaster class battle. Your slime must fight through several levels, and winning the match gives you a prize.
Dragon Warrior/Quest VII
The Arena doesn't appear in this game in any form.
Dragon Quest VIII
Morrie's Monster Arena is located southeast of Pickham. It's is here where the Monster Series and the main series meet up, in what is one the more enjoyable side quests in the game. To take part in this Morrie's Arena you must recruit monsters to create a monster team of three. That team can work it's way through the Arena by winning eight ranks (G-S) with three rounds for each rank. You have no control over your monsters, but you can level them up outside the arena by leveling your hero up. You start off with three monsters however by the time you reach Rank-S you have a reserve group and a second monster team at your disposal.
The Monster Series
In the monster series of games, you main quest centers around The Arena. There are differences in each game but as a whole you can give your monsters commands and as you win you unlock a new Rank. Dragon Quest Monsters Joker is the only exception. Joker give you two arena's one that you have to fight in to complete the game and one that you can fight in for fun, however in the fun one you can't control your monsters.
