Besides, to the best of my knowledge, it was possible that Attack forme Deoxys on FireRed could link-battle between Defense forme Deoxys on LeafGreen, was it not? That clearly contradicts part of the first statement.
The reason Attack Deoxys and, say, Normal Deoxys could fight each other over a link was because they were using the same location data with different stats.
Deoxys in Diamond and Pearl has 4 locations programmed: Normal, Attack, Defense, Speed. They are counted as 4 completely separate Pokemon, as in each has it's own movepool, STATS, ability, type, egg data, height, weight, etc.
Castform's different forms don't have separate entries, he just has 4 sprites and a few bits of data that tell the game to change his type accordingly. This is because the only thing that varies by form is Type.
Wormadame's three forms each have different entries in the game, because each has different STATS.
So, Wormadame and Deoxys are alike, in that regard.
SHAYMIN and GIRATINA have only ONE LOCATION EACH in Diamond and Pearl.
The reason Bulbapedia is INCORRECT is because the programmers have NOT YET done any coding that could lead us to believe it is possible to have:
*2 forms of one Pokemon, who
*Have different stats
Yes, it is possible they could code some kind of elaborate workaround, however, it is extremely unlikely. Mark my words, Giratina and (100% PROVEN) Shaymin will act like Deoxys in Advance in that you CANNOT use Land or Another form in Platinum at all. They will use the same location data that the old Giratina and Shaymin will use. They've done this in the past, we know they can and have done it this way in the past. We have no evidence to support that they are going to drastically alter a fundamental piece of the game's structural code JUST so you can use Another form Giratina in Platinum.
New locations cannot just be "added," they are planned from the beginning or they do not exist. Besides the fact that the number of locations in the Pokemon data is a "nice" number already (probably a hex number), if they add new locations, they cannot allow Platinum to battle or trade with Diamond or Pearl at all, for fear of hackers crashing the game when sending out NONEXISTANT (to DP) Pokemon. If you tried to send out a "new" location Pokemon in a battle, for instance, you would see MissingNo or a Bad Egg or something similar, and the game might crash.
Oh, and some form of Regigigas that HAS NO PROOF OF EXISTANCE. Do you know why people thought there'd be a Sky Regigigas? Do you know where this "rumor" came from? People who blindly believe anything they're told (so long as it's what they want) without ever checking sources, or checking that the info they're getting is correct.
For the last time. There is no proof on any Japanese site, not even a mention on a blog someplace, of a new form of Regigigas. It's fabrication is purely of the misinformed English-speaking fan community.
It's as real as a fanfic.
If you doubt anything I tell you, go do some research on the game's Pokemon location data; go look up how MissingNo works, and why he even shows up in the first place.