not sure how but i dont got it

Final Form...

I know that there is at least valor, wisdom, master, anti, and final form but for some reason I see that I should have it before I fight Xigbar. can anyone tell me where I should have gotten it?

final form becomes available after the cutscene at the skyscraper in the WTNW.
just keep driving, and it'll eventually come up, randomly.

Alright, thanks.

I didn't get mine till the battle with siax, and I just though the game screwed up.

Really, if you really need final form, go to a save point anywhere when you have a full drive bar, and just go into drive. Then just go back to the save point and leave the world, come back, the rinse and repeat.

But I really don't think you need it though, I was able to get through all major orginazation members without it.

Here's a nice little trick that you can use, courtesy of the Official Strategy Guide:
1. Go to the alley you were in when you first entered TWTNW
2. Leave the alley
3. When a swarm of heartless appear, change into either Valor or Wisom form
4. If you don't get final form, take this opportunity to level up
5. When your drive gauge is almost out, hurry back to the alley and go through the portal to Twilight Town without changing back. You are now back in Normal Form, with a full Drive Gauge!

Here's something similar for Master Form:
1. Go to Mulan's world (forget the name...)
2. Go from the Village to the Ridge
3. Fight all of the Heartless and Nobodies (you may have to exit and enter the area a few times)
4. When they're all gone, change into Master from and bust up all of the carts and stuff to collect orbs.
5. Enter/Exit the area and collect orbs untill your Drive Gauge is low
6. Return to the save point, leave the world and repeat.

Drive gauge must have at least 5 or it won't work.