We all know Golden Sun, correct? Cool.
Fun fact: Golden Sun was my first JRPG (not counting Pokemon); I didn't discover Final Fantasy until I was in high school. It's always had a special place in my heart because of this, until about a year ago, when I decided to do a challenge run through Golden Sun and The Lost Age where I collect the absolute bare minimum number of Djinn (Flint and Fizz in GS, Echo, Spring, and Shade in TLA). Having played more JRPGs since my previous playthrough, the game's flaws became more apparent. The story and characters, for instance, I found phenomenally uninteresting, but let's focus on the gameplay and character customization - the Djinn system.
For those who need their memories refreshed, throughout Weyard (the land of Golden Sun) are a grand total of 72 elemental critters to collect and equip called Djinn. Djinn can be in one of three different modes - when they're in Set, they can change the stats and class of the Adept whom they're equipped on, as well as grant access to different kinds of Psynergy. Using a Djinni's unique ability in battle sends it into Standby mode. Standby Djinn don't impact an Adept's class, stats, or Psynergy, but can either be put back into Set or be used to summon creatures to deal massive damage to all enemies. After being summoned, they enter Recovery mode, where they can't be used for anything until they automatically return to Set mode.
I have to say, I actually think Golden Sun's class system is pretty neat. I really like the idea of these elemental tokens that can be mixed and matched and rearranged for different class and party combinations. The problem is that unless you need to teach an Adept Growth to get past an obstacle, there is absolutely no reason to experiment with it - all you need are the summons. Golden Sun's damage calculation is kind of odd - when it comes to summons, the higher the maximum HP of the enemy, the more damage summons do, so even the lowest class of summons, while nearly useless for random battles, still deal good amounts of damage against bosses. And as soon as you get three or four Djinn per element, even the random battles become a joke. All you need to do is spam your strongest summons, run around a bit so your Djinn recover, put them back into Standby, and repeat. To be fair, several of the bonus bosses in The Lost Age are designed with this summon spam tactic in mind (I hate you, Star Magician.) but it's a shame the gameplay that comes before them doesn't have that level of challenge.
Golden Sun certainly is not the only game to feature a summon mechanic, but it any other game that features them, they usually have high costs attached to them via MP or mana or charges, and can't be restored simply by running around for a few seconds. It's also not the only game to feature a ridiculous game-breaking mechanic, but not a lot of them give you that mechanic as early as Golden Sun gives you your summons. Spellblade, Dual-Wield, Rapid Fire, Dualcast, and Mix might be game-breaking in Final Fantasy V, but they aren't usually unlocked until the tail end of the game, after a fair amount of grinding, or both.
Even without the summons, some of the Djinn's abilities are just ridiculous. It's fine that they feature unique abilities that Psynergy can't typically cover, like Kite, which grants its target two actions the following turn, or Lull, which automatically ends the turn when it's used - these can open the way to some interesting strategies. But what about Flash, Granite, or Shade, which reduce all incoming attacks that turn to scratch damage? You can win pretty much any battle in the game by doing the following:
Turn 1 - Isaac uses Granite, everyone else attacks.
Turn 2 - Isaac sets Granite, Garet uses Flash, Ivan and Mia attack.
Turn 3 - Isaac uses Granite, Garet sets Flash, Ivan attacks, Mia heals if necessary.
Go back to Turn 2.
(I know that thanks to the class system, anyone can be a healer, but come on. You're going to keep things monoelemental, Mia's going to be the healer.)
It really is a shame that the summons are the focus of the gameplay instead of the classes, but I think there might be an interesting fix to this system - removing the summons entirely, and the Standby phase along with it, having only Set and Recovery. When Djinn are in Set, they work the way they already do, but using their abilities in battle puts them directly into Recovery. And instead of being queued up for Recovery like the current system, where one Djinni recovers per Adept per turn, each Djinni would have its own unique recovery time, with the Djinn that feature basic attacks or light healing recovering much faster than the barrier or revival Djinn.
Psynergy would work the same way it already does, but if you want to use the really powerful Djinn abilities, you need to decide whether it's worth X turns in a weaker class. This system probably has some flaws to iron out, and yes, you would lose the pretty summons, but it could potentially result in a more balanced gameplay system that emphasizes prediction and risk management over abusing overpowered abilities. I have RPG Maker VX Ace, so I might mess around with something like this.