Supposedly what the text says (in the ad):
New details have been released on Square's first Final Fantasy game in a long time for a Nintendo system.
The Gamecube Final Fantasy: Crystal Chronicles game indeed is turning out to be more of an action RPG. Each character has a Zelda-like heart meter to represent their life, that and their information and portrait appears around the borders of the screen, much akin to Secret of Mana. Four players can play simultaneously, by using GBAs as controllers. It would seem the entire party's vital stats get displayed on the GBA screen, but its hard to make out exactly how this works at this point. Luckily, more information is promised soon.
As for the combat system, it seems a mix of Final Fantasy tradition and Secret of Mana-style fighting. Context sensitive buttons assigned to the green and red buttons on the Gamecube controller (and presumably the GBA) seem to control character actions such as fighting, picking things up, dropping them and defending depending on the situation or environment. By co-operating with other party members/players you can link up attacks in great combos for added damage.
Magic can be linked to, and it would seem there environment can effect its power. The standard Final Fantasy array of spells is already in place, such as Fire, Thunder and Blizzard, and in order to use them characters must have magic stones.
The plot in this title returns heavily to the mythos of the crystals as seen in earlier games. Basically, the crystals bless people's lives and support the world. They grow or exist in proportion to the need, so there will be small crystals and large crystals, depending on where you go. Every year, it is necessary to purify the crystals with Mana Water. But Mana Water is not exactly easy to find, sometimes it might be in across a mountain, or in a cave, or on the wide-open sea. You never know. And because of this, people have set up teams called Crystal Caravans to go search for them (which are the wagon travellers seen in earlier artwork). The story begins on the outskirts of an obscure village with a youth (who is most likely involved with a Crystal Caravan).
That youth and how his or her story will unfold is influenced by who you pick at the start of the game, though to what extent is not known. You can choose from four different tribes or races from the game, each with their own special features of course. There are the incredibly odd Yulk, who look like a cross between knights, dragons and chocobos, and are blessed with the power of magic in the armor on their bodies. There are the graceful, agile and limber Selkie, who seems to be a race of thieves of blue hair who follow the philosophy of thinking of yourself first and others later. Also appearing are the peaceful Clauvert, a rural, down-to-earth tribe who co-exists with nature and do not like conflict. Last and smallest of the races, but hopefully not least, are the Lilty. They are a race of small beasts who rather look like overgrown acorns, generous with frank and curt personalities, these people's lives revolve around trade and business.
From screenshots, art and details, it looks like Square's Crystal Chronicles is shaping up to be quite a promising game."
But, I have no source as I found it on another message board...