Bringing this up from RoA and after some testing myself: http://www.smogon.com/forums/threads/new-platinum-glitch-giratina-forme-change-stat-glitch.3604281/
Before anything else, this glitch is Platinum exclusive but it seems it was legal in Wifi anyway.
French site that first documented this
Quoting from the website:
This is the spread I used for this testing(Don't mind this, is the Physical attacker set from Gira-O):
EVs: 84 HP / 216 Atk / 96 SpD / 112 Spe
Adamant Nature
That means:
If we perform this fast glitch, changing their items on the PC while on our Party we will get:
Now the question is, should we allow this on DPP Ubers? It could be quite annoying just for the fact that you won't exactly wouldn't know which Giratina is really and which base stats has. You could be facing more bulky Gira-O or way stronger Gira-A(Choice sets with those stats looks really cool).
You cannot transfer this to later generations just for the fact that in order to transfer from DPP to B/W, they have to be in the Box itself, and if you do that, their stats get reset to normal.
(Also I don't exactly know how we could implement this in the teambuilder, maybe a button to change their base stats to the other form?)
Gallery with All Stats
Before anything else, this glitch is Platinum exclusive but it seems it was legal in Wifi anyway.
French site that first documented this
Quoting from the website:
The french site explains "After that, as long as you do not change its held item outside of the PC it will remain in this form, even when saving. Even better, before the DS online services closed, it could be used online, whether in HG/SS, or by transferring it to D/P. Imagine sporting a Giratina with Choice Band and the stats of the Origin Forme!"
EVs: 84 HP / 216 Atk / 96 SpD / 112 Spe
Adamant Nature
That means:
Giratina Alternate:
Level 100.
Ability: Pressure
Item: None
HP: 462
Attack: 319
Defense: 276
Special Attack: 212
Special Defense: 300
Speed: 244
Giratina Origin:
Level 100.
Ability: Levitate
Item: Griseous Orb
HP: 462
Attack: 363
Defense: 236
Special Attack: 248
Special Defense: 260
Speed: 244

Level 100.
Ability: Pressure
Item: None
HP: 462
Attack: 319
Defense: 276
Special Attack: 212
Special Defense: 300
Speed: 244
Giratina Origin:

Level 100.
Ability: Levitate
Item: Griseous Orb
HP: 462
Attack: 363
Defense: 236
Special Attack: 248
Special Defense: 260
Speed: 244
If we perform this fast glitch, changing their items on the PC while on our Party we will get:
Giratina Alternate:
Level 100.
Ability: Pressure
Item: None
HP: 462
Attack: 363
Defense: 236
Special Attack: 248
Special Defense: 260
Speed: 244
Giratina Origin:
Level 100.
Ability: Levitate
Item: Griseous Orb
HP: 462
Attack: 319
Defense: 276
Special Attack: 212
Special Defense: 300
Speed: 244

Level 100.
Ability: Pressure
Item: None
HP: 462
Attack: 363
Defense: 236
Special Attack: 248
Special Defense: 260
Speed: 244
Giratina Origin:

Level 100.
Ability: Levitate
Item: Griseous Orb
HP: 462
Attack: 319
Defense: 276
Special Attack: 212
Special Defense: 300
Speed: 244
Now the question is, should we allow this on DPP Ubers? It could be quite annoying just for the fact that you won't exactly wouldn't know which Giratina is really and which base stats has. You could be facing more bulky Gira-O or way stronger Gira-A(Choice sets with those stats looks really cool).
You cannot transfer this to later generations just for the fact that in order to transfer from DPP to B/W, they have to be in the Box itself, and if you do that, their stats get reset to normal.
(Also I don't exactly know how we could implement this in the teambuilder, maybe a button to change their base stats to the other form?)
Gallery with All Stats