I couldn't finish 'em. Looks like this's gonna get complicated.
1st Battle Edit
Hits twice for around 200 damage to the front row, usually striking twice in a row. Howling Gale deals around 300 damage and inflicts Sap. Tornado brings a single target's health down to critical. This combined with Howling Gale will cause the target to die from Sap. Buffet hits the party for 200 damage and can cause them to be Stunned. This can be followed by another attack.
Keep Slow up on the boss. Inflict as much damage as you can with your front liners and possibly spell casters. Keep the party healed with Cura, and use Hi-Potion or Cura on anyone struck by Tornado. Quickly Raise or use Phoenix Down on anyone killed by a combination of Tornado + another damage source. Buffet can be annoying, but it's not lethal unless used on someone affected by Tornado. This fight takes a little bit of time due to the bosses large health pool. Keeping your party healed is the only real obstacle here. Use two Red Mages or White Mages and two Monk/Warriors for an easy fight.
2nd Battle Edit
This battle follows immediately after the first one. Your party is healed to full. Vata now Absorbs Wind. Uses Jump to deal high single target damage for around 600+. Otherwise will Thunder Breath for 150+ damage to the party or Lancet for 100+ single target HP Drain. Repeats this for several turns then Flee. This fight is scripted.
Keep your health up and continue attacking. This battle will end shortly when the boss uses Flee.
3rd Battle Edit
Lancet is harmless. Wild Dance is just a bunch of random attacks that deal small amounts of damage to your party. Thunder Breath hits for around 600+ to your entire party. Buffet can Stun your party and inflicts 700+ damage to your entire party. Howling Gale can inflict Sap, but only inflicts 300+ damage to one of your characters.
Tank & Spank. Keep Protect and Shell up on your party. Keep healing your party with Cura. Use Argy to give your group any needed buffs or healing that your other characters cannot apply. Use Boost Jump to inflict massive damage. This encounter isn't difficult using the above strategy. Vata uses Lancet a lot, which does basically nothing.
4th Battle Edit
This battle happens on Mt. Wells. Vata will use the same moves as in the previous battle. However, this fight is much harder. Jump deals massive damage any probably kill any White Mage, Black Mage, or Summoner instantly, even with full HP. His other attacks will do about the same amount of damage. However, what makes this battle so difficult, probably the most difficult battle the Warriors of Light have faced so far, is that there are only 4 characters available and he is very fast.
The player will need at least one character who can cast Curaja. Casting protect on a Mage or Summoner if the player doesn't want them to die because of Jump. Vata is very fast so the player must heal continuously. Thunder Breath is a threat as it will damage all characters for nearly 600. He can spam Thunder Breath before using Jump or Buffet. If a character gets Knocked Out, others may be killed soon after as a domino effect. Phoenix can revive all characters, but with 99 MP. A Dragoon can evade his Thunder Breath and Buffet by using Jump. In this battle, his HP is not very high and Lancet does just about 200 damage. He will use Lancet and Wild Dance when his HP gets low, so the player can win easily if they are lucky enough. It may takes several tries for the player to defeat him. If they cannot, try to gain some levels or change jobs.
5th Battle Edit
Vata is as strong as he was on Mt. Wells, with some new moves. However, this time, the party should be much stronger so he is not as difficult as he was anymore. Fighting halfway through the battle and he will start using Holy Breath and Jump to inflict more damage.
Vata can be defeated with ease. Holy Breath is a new attack which can hit about 1200 to a front-row member. A White Mage is enough to keep the party healthy while others keep damaging him.