I received the Japanese Shiny Jirachi event Pokemon from someone a couple months ago. I decided to go check it's IVs and it had all 6 of them. Is it possible for an event Pokemon to have all 6 IVs? Thanks.
I assume you mean they're all full 31/31?
With the exception of event Pokemon that are locked to have certain IVs(Which I don't think this one is), it is entirely possible, but incredibly unlikely. The Pokemon is most likely a hack, but it's also possible someone spent a very long time soft resetting for all 6 IVs and then cloned it for trading.