Regarding Keldeo and Keldeo-R,
I have seen some sources conflicting, so I am going to ask here. Most say that Keldeo must be in Resolute Forme if it knows Secret Sword, and in Ordinary Forme if it doesn't know the move.
However, would the following be possible?
1. Obtain a Keldeo (Ordinary Forme) by event in B2W2
2. Trade the Keldeo to BW
3. With Virizion, Terrakion, and Cobalion, teach the Keldeo Secret Sword at the Moor of Irricus. (Since the Resolute Forme did not exist in BW, it will remain in the Ordinary Forme.)
4. Trade the Keldeo back to B2W2
As far as I know, Keldeo only changes forme if taught Secret Sword at Pledge Grove, a BW2 Area. If taught the move at the Moor of Irricus in BW, it will not change forme.
Notably, if it is possible to teach Keldeo Secret Sword without changing it to Resolute Forme, then this will remove all competitive use of the Resolute forme, since the Ordinary Forme will be identical, but will not reveal its moveset.