I'll copy-past EAI's answer on the matter:
"Hmmm - hmmm, tricky one
I'll probably need to discuss it with Marion and Emily first to properly discuss what's fair in this case
Essentially the trade 'was done' last year for the account which you now locked.
Add to that, technically we don't want those who are quitting giving away all their Pokémon to members just like that but that isn't the case here and you have proof that a valid deal was set up beforehand.
Strictly speaking (and because we don't want to piss off the FB mods on Serebii) the trades have to occur on the forum where both players are playing. In this case, UPN would be the safest choice and I'm not entirely sure why Reyzadren can't trade over there
had a brief discussion
Basically: the trade is happening now and not in the past. Serebii FB (UC) and UPN FB are separate entities meaning trades can't occur between these two games. I'm not sure in which game Rayzadren wants to stay (if he does) but the trade has to occur on UPN by both participants"
In short, they say you can gift it to me in UPN (since gifting is now allowed), but not on Serebii.
"Hmmm - hmmm, tricky one
I'll probably need to discuss it with Marion and Emily first to properly discuss what's fair in this case
Essentially the trade 'was done' last year for the account which you now locked.
Add to that, technically we don't want those who are quitting giving away all their Pokémon to members just like that but that isn't the case here and you have proof that a valid deal was set up beforehand.
Strictly speaking (and because we don't want to piss off the FB mods on Serebii) the trades have to occur on the forum where both players are playing. In this case, UPN would be the safest choice and I'm not entirely sure why Reyzadren can't trade over there
had a brief discussion
Basically: the trade is happening now and not in the past. Serebii FB (UC) and UPN FB are separate entities meaning trades can't occur between these two games. I'm not sure in which game Rayzadren wants to stay (if he does) but the trade has to occur on UPN by both participants"
In short, they say you can gift it to me in UPN (since gifting is now allowed), but not on Serebii.