You're getting Tales of Symphonia on the PS2? It's actually better on the GC, although there are extras in the PS2 version, and they only made it for PS2 in Japan.
Tales of Symphonia has a real-time battle system. You control one out of four characters (you can choose any of them, although I always preferred Lloyd) and you hit um...the green one to attack. X, I think? You can also use circle along with a direction on the d-pad for a special attack. You can set your AI teammates to battle a certain way, or you can do multiplayer during the battles and have your friends control the other characters. You see the enemies on the map before you fight, so you can try to avoid them if you want. There's no random battles, in other words.