I was going to reset the flag for this event, but I decided to look at the Type: Null I already had from this event instead. I used PKSM editor to look at his IVs.
Mine has:
Nature: Jolly
HP: 28
Attack: 31
Defense: 31
Sp.Atk: 31
Sp. Def: 31
Speed: 28
.. so it seems they aren't set, and aren't guaranteed to be bad.
So, the common conception of 3 perfect IVS and the rest random seems to be accurate.