Final Fantasy Tactics Advance/Twisted Flow

Twisted Flow is an interesting battle, introducing you to the concept of Totema. The Totema are units who are guarding the crystals created by the Palace to keep Ivalice as it is. The Totemas are really the bosses of the games, and will exemplify that throughout the rest of the game.

Pre-Battle
Not much to say here. Do missions if you like. Also, if you want the next mission to go easier, make sure you have 3+ rangers, a healer and the rest of your team melee fighters. It'll make one of the ways to fight the boss much easier. If you are going to be using a white mage, make sure they know Life.

Strategy
Whoa, look at the field. Some of those guys will kill you, and kill you good. Famfrit is probably the most worrisome. He is big, powerful, and can deal a lot of damage in one attack. His ability Lightspeed will bypass reaction abilities, making things like Counter worthless. The floateye genus don't have much going for them in the long run, so they shouldn't be to hard to take out in general. You have to watch out for the Ahriman with Roulette though. Roulette chooses a random ally or enemy and KOs it. That is why a white mage with Life is necessary.

Now here you could really do one of two strategies. The mission requirements to win are to defeat Famfrit, and that is it. Many people beat this level without even touching the floateyes. You really have the choice - go for the fast kill and possibly make sure Famfrit doesn't take a turn or your dead while all his floateye friends pound at you, or get rid of the floateyes first and then smash the totema into oblivion. Your choice. If you have guys level 10+, the former would probably be easier, just since the Ahriman with Roulette will be constantly using it, making any attempt to do the former much harder, especially if your white mage is KOed.