Here's a great game that you should steal ideas from:
Name: Valkyrie Profile
Publisher: Enix
Developer: tri-Ace
Year: 2000
Why the game is good: Pretty much everything about it. Graphics, music, gameplay...wherever it counts, VP's got you covered. VP basically throws away most RPG conventions and presents something original in every way. The game is based on Norse mythology, so if you're into that, character names and items will be familliar, and so will some of the events that occur in the game.
Basically, you're a Valkyrie, and your job is to collect souls for the great battle that looms over the horizon--Ragnarok. What you do for the majority of the game is travel the world, looking for dead warriors and killing lots of undead along the way. The dungeons play out like side-scrolling platformers, which is very cool. The battle system is excellent, and it's my favourite part of the game. I'm going to go into the battle system in detail, because you're working on a game, and you'll need details.
VP's battle system works like this: Each character is assigned to a button on the controller. e.g. Valkyrie is assigned to the square button, Arngrim is assigned to the circle button, etc. If you want a specific character to attack, just press the corresponding button. By pressing buttons at the right time, you can string together combos, and you'll need to if you want to get anywhere in the game.
Each character's attack adds energy to a meter. Each time you successfully strike an enemy, the meter fills up (but slowly empties itself). If you can fill up the meter in a single turn of combat, then you have a chance to "Purify Weird Soul" (PWS for short). These are essentially super-powerful attacks that are unique to every character. Using a PWS will use up a portion of the meter, but the PWS can fill it back up. This allows you to use another PWS by another character! You can do this up to four times (1 per character), but you have to know how much energy each PWS adds to the meter. If you can get more than 50 hits in one turn, then any further damage you do in that turn is doubled. The weapons you equip determine how many attacks each character can perform. Each character has up to 3 unique attacks, and you can execute them in any order you want.
Using a PWS adds Charge Time (CT) to the character that executed it. While a character has CT on him, he can't use PWS. CT decreases by 1 each turn, but you can eliminate it faster by collecting purple gems, which are acquired by nailing the enemy with combos. You can also collect blue gems and treasure in this manner (blue gems raise EXP earned after battle). If you can juggle the enemy (i.e. nail him while's he airborne), then you raise your chances of getting gems/treasure (I think--I don't remember well).
What I like about tri-Ace's RPGs is that their characters aren't just "stats" in battle. In most RPGs, you have your typical strong guy who can do big damage, but that's all he can do. However, in a game like Valkyrie Profile, your guy may be strong, but can he effectively hit an enemy? Does he hit high or low? How many hits per attack? How much energy does he add to the meter?
Magic users are a special case in VP. They attack only by using magic, and they have their own super attacks. They have unlimited MP, but they can only use magic every other turn (i.e. their CT increases by 1). A magic user's PWS comes in two forms: an extended version of the current magic they're using, or Great Magic. Great Magic requires a special item in order to use them, but they strike all enemies, and hit multiple times.
I think that's everything there is to know about the battle system.