I don't have much to offer, but here is what I have:
Shiny Entei Hardy, Inner Focus from Virtual Console 3 best IVs
Shiny Entei Bashful, Pressure, perfect IVs
Shiny Mewtwo, Quiet, Pressure, poor IVs
Shiny Latias Careful, Levitate, 3 best IVs
Shiny Mewtwo Rash, Pressure poor IVs
Shiny Sivally Hardy RKS Sytem, 3 best IVs (non event)
Shiny Landorus Hardy Intimidate poor IVs
Truthfully, I don't any events I can part with. I sadly parted with my extra Marshadow. I have to update this list since it has changed. I have an extra Magearna, but that is the only event I have an extra of now. So sadly at this point, other than what I have listed, or now have to update later, I still don't have much to offer in return. I actually don't have most event Pokemon as it is, just the recent Legendary events that have come out, and I've even missed some of those. Thought this thread was dead, but I'll update the list a bit later.