One thing that worries me a bit is the one related to FF material, in kh3, especially that of secret bosses and summon .

Now here's what I think it would  work   in kh3

Secret Bosses

Sephiroth normal form + sephirtoh Safer form

ghilgamesh

Kefca

Caius ballad

Ardyn

Lightning

Noctis

Balthier +fran

Vaan +penelo

Ultros + thyphon

And as dlc the ff7 weapon ( diamand , runy, emerald, Sapphire, ultima , Jade , and omega )

 

Summon

The Gullwings ( the trio yuna , rikku and paine) as evolution of the summon Tinker Bell ,were Yuna will care for us, rikku will strengthen us, and paine will cause negative status to the enemies, and for the final attak they use Delta Attack

Nanaki  as evolution of the summon simba   which, in addition to carrying out a series of fire attacks, performs asfinal move the Infernal Flames attack.

The chocobo as a special summon  to be used to move more quickly through the open world areas

Bahamuth from ffx  , classic summon which also acts as a secret boss

http://sakuyamon.deviantart.com/art/Kingdom-Hearts-Summon-Bahamut-318752317

And as summons that I must first defeat  : ifreeta, ramwel and shivalry from world of ff, since I think they have a personality  perfectly to interact with sora

http://finalfantasy.wikia.com/wiki/File:WoFF_Ifreeta.png

http://finalfantasy.wikia.com/wiki/File:WoFF_Shivalry.png

http://rpgvaliant.com/world-final-fantasy-adds-rikku-ramuhs-granddaughter-gets-screenshots-shantotto

and as dlc

the trio mogle , tomberry  and kyatus

http://finalfantasy.wikia.com/wiki/File:Mog_Tonberry_Cactuar_Art_T0.jpg

cat sith from ff7 

What do you think of it? , Is there any chance of finding them in kh3?

thats an awesome list I hope that they can make it all fit in since there wont be as many worlds as in Kh2

Safer Sephy would be cool

Gilgamesh is a must

Bring back Bahamut since he was scrapped from KH1

I personally think Sephiroth shouldn't be the secret boss this time around. And I think Noctis would be a really good pick.