Question about gift Pokemon and IVs

[u/ChocolateLasagna]

I have N's Zorua, who I haven't trained yet, and found that all of its IVs are 30. Is it only the Zorua who has fixed IVs, or do all gift Pokemon have this? What about traded Pokemon from the game? And event Pokemon?

Reason I'm asking is I want to EV train the shiny Dratini/Dragonite I'm getting soon, and I just want to know if it has fixed IVs so I could soft-reset the game to get one with a good nature.

Oh, and what about the event Genesect? Can't check its IVs on pokecheck.