These types of games are usually good stand-alones, but it always helps if you played the previous games in order to get a deeper understanding of the story, since the characters will probably refer to events that took place during the PS2 game. However, since this is a Nintendo game, and they don't expect the players to have both consoles, my guess is that those references will be minimal.
I'd recommend playing FFXII on the PS2 as well though, since it's a great game, albeit a little long (took me 60 hours to beat without doing any sidequests. I didn't die that often either.)
