>>56406293Should be fine, as it was a DP event. Same goes for some of the Shaymin distributions.
Don't quite me on this, but I don't think receiving these on Platinum would be an issue, as they don't have your PID/SID anyway.
Main things to keep in mind is that DP Darkrai and Shaymin caught ingame are illegal, and Arceus caught ingame using the Azure Flute is always illegal. (still useful for the HGSS event though, as having both a distributed Arceus and Azure Flute Arceus will let you do the Sinjoh Ruins event twice)