Um dude... EM is NOT Xaldin... sorry to tell you. It shows nothing from Final Mix, in which we see the Enigmatic Man. I know because I own FM, and a mod chip, so I have played AND BEAT Final Mix. EM uses the Beam Sword of Third Power, and Red and Blue Chromatic Lightning attacks.
Xaldin has already been said to be primarly a weapon based fighter, and a stealthy one at that. Then again, I dont guess you read japanese, which is not really my fault.
That, and as far as EM goes, for being an Unknown already revealed, he has a better chance of being, Zexion. Actually, there is more evidence backing that than him being Xaldin. That and this fact:
XALDIN IS A ROOKIE!
Did you NOT play CoM? The lower your number value is, the higher in rank you are! Marluxia is like 11, andf technically (if it was not for the fact that Castle Oblivion belonged to him from somehow inheriting it) He was a low-order member of the Organization. What the XIII in your little picture means is that it is talking about the Official name of the Organization, which is this:
XIII Organization.
I have stated my evidence, and found your theory false, sorry to break up your hopes kid.