Battle Mode

Battle Mode is an option in both GBA Golden Sun games. It is where players can battle and practice different strategies against monsters and bosses from the game and against friends with use of a link cable. No coins or EXP are earned in Battle Mode. With this mode you can use all the items and Djinn that you currently have in your possession. All battles take place in a colosseum setting similar to Colosso and play the standard Battle Theme(s).

Lobby
In the Lobby you can talk to all the Adepts you currently have in your party. Other than that there are just a bunch of NPC's you can talk to, as well as one Great Healer, who provides his usual services. You are not allowed to use Psynergy or save while you are in the lobby, with the exception of battle records which get automatically saved by the woman at the counter. However, if you talk the lady in the lower left corner while holding a shoulder button in Golden Sun: The Lost Age you can listen to the game's Sound Test option.

Monster Battle
The Monster Battle mode is initiated when you have no link cable inserted into the console. You must talk to the woman at the counter and she will tell you to stand in the white circle when you are ready. With Monster Battle you can fight in an endurance-style series of battles comprised of any of the monsters you have already battled in the game file chosen at random, including boss battles (but not including Djinn), and the chain of battles only ends once your party is annihilated. The amount of battles you have won prior to defeat will then be recorded as a high score in the Battle Lobby for that file. Enemies from Golden Sun will not appear in The Lost Age and vise versa. In none of the battles in the chain are you allowed to run. Any items used in battle will automatically be returned to the party as soon as they are done battling and choose to quit.

The statistics of the enemies fought in the Monster Battle increase directly in proportion to the level of the party, and further increase as the chain of battles progresses successfully; the idea is that it lets the potentially powerful and sturdy party of a game file at its endgame fight more appropriately difficult battles than in the main game. Whether the game file involved is being played in Hard Mode also affects enemy statistics appropriately. The statistical buffs the normal enemies receive apply every bit to the bosses, though, and since any boss you defeat in the game file is eligible to appear in the Monster Battle, it is entirely possible to fight a stronger-than-normal version of Dullahan multiple times in a row in a Battle Mode of a game where the party has already defeated the normal Dullahan.

It would be very hard to survive a Monster Battle battle against Dullahan if one uses a party comprised entirely of level 99 characters, even if everyone has the best possible equipment and are in powerful classes such as Ronin using powerful offenses like Quick Strike and the Sol Blade's Megiddo unleash. So if one wants to try to get as high a score as possible in Monster Battle with a level 99, optimized party, the file involved should not have yet achieved the defeat of the final boss and the four optional bosses Valukar, Sentinel, Star Magician, and Dullahan. The other bosses fought prior should be much more manageable whenever they happen to appear in Monster Battle.

Incidentally, the scaling of monster statistics along with Hard Mode's scaling, only applies to monsters present at the beginning of the battle, so monsters spawned mid-battle (such as Star Magician's Balls), will have their regular stats.

Link Battle
With the Link Battle option you may battle a friend with a copy of the same game to see who's better; however, you cannot link the original Golden Sun to The Lost Age. In this mode, you are restricted to the use of only three adepts each, and a time limit is set on your turns, with characters who are not assigned turns being forced to defend. All of your battle wins will be displayed on the wall. Other than for bragging rights it serves no real purpose. Despite this minor role, the Link Arena has its own music, track number 45 in the aforementioned sound test.

Quotes
When spoken to in The Lost Age, the seven Adepts will say different things depending on who is in the starting lineup (i.e. one of the first four Adepts)

Isaac

If Isaac and Felix are both included among the first four Adepts

"It's our turn. Let's go, Felix."

If Isaac isn't one of the first four Adepts but Felix is

"OK, we're set, Felix. But remember, you're calling the shots, all right?."

If Felix isn't one of the first four Adepts

"I'll fight enough for both of us..."

Garet

If Garet and Felix are both included among the first four Adepts

"Hey, Felix, I'm all set to show you what I've got."

If Garet isn't one of the first four Adepts but Felix is

"What? I have to take a break? Why do I have to do that?"

If Felix isn't one of the first four Adepts

"If you don't want to fight, that's fine. We'll do better without you, no problem."

If spoken to in Golden Sun

"I can't wait, Isaac! Let's go get 'em!"

Ivan

If Ivan and Felix are both included among the first four Adepts

"If you want me to fight, I'll do it, but don't expect anything amazing from me."

If Ivan isn't one of the first four Adepts but Felix is

"There's something really sad about being told to stay behind."

If Felix isn't one of the first four Adepts

"Huh? No way! Please fill in for me!"

If spoken to in Golden Sun

"Yes, I'll always help Isaac in battle!"

Sheba

If Sheba and Felix are both included among the first four Adepts

"You don't even want to try? I'll show you my power."

If Sheba isn't one of the first four Adepts but Felix is

"Don't you want me with you anymore, Felix?"

If Felix isn't one of the first four Adepts

"Good luck, Felix! If you want me, you know where to find me."

Jenna

If Jenna and Felix are both included among the first four Adepts

"Hey, I'll do my best if you do yours!"

If Jenna isn't one of the first four Adepts but Felix is

"OK, I'll be waiting right here. Do your best, and hurry back."

If Felix isn't one of the first four Adepts

(Visibly angry) "Wait, I say I'll fight, and then you back out of it? What's that all about?"

Mia

If Mia is among the first four Adepts

"I'll do the best I can!"

If Mia isn't one of the first four Adepts

"That's fine, I could use some rest anyway."

If spoken to in Golden Sun

"I'll do my best."

Piers

If Piers and Felix are both included among the first four Adepts

"All right, Felix, we'll do it together!"

If Piers isn't one of the first four Adepts but Felix is

"Are you trying to tell me something, Felix?"

If Felix isn't one of the first four Adepts

"So it's just me. Is that all right? I'm a little nervous."