in my opinion your trying to break the game more so than it should be, I mean... Yeah black pokemon would be cool, but they don't need special stats, nor do shinys... If I recall, the real games don't even give the stats that we recieve for shinys found here.
I think you have now confused your suggestion. There is no mention of this option in the original post and none in the poll either. I suggest you modify your original post and poll to add the option of black pokemon (or different coloured shinies) with normal shiny IV boost as well as the option of having the MAX IVs.
Without the extra option discussion is confusing and you won't know if players like your black pokemon idea if they are against having them max IV.
I dislike this idea very much.
I would rather see a system put in place where shinys caught have a chance to have 25-31.
If you could catch a shiny with perfect stats it would be too easy to obtain them even with a hard catch rate. I mean look how many people caught S Snorlax over the last event.
In my opinion shinys are more than enough. I personally very much dislike those Pokemon MMOs which have endless different version of the same Pokemon. Normal, Shiny, Rainbow, Black, Dark... The list could go on forever...
And by the way: What would be the difference between a S Charizard and a Black Charizard?