Some results:
JAP 6IVs Ditto x ENG 6IVs Rotom
Batch of 150 eggs: no shiny
When I'm using a 6iv ditto or a couple from diferent species, I often confront a long shiny drought (my shiny ratio is like 1/600 eggs)... Very disappointing. So I decided to increase my flawless japanese pokemon collection and use them in my breedings. Got a perfect quiet honedge and tried this desperately:
JAP 5IVs (0 speed) male Honedge x ENG 5 IVs (0 speed) female Honedge
Batch of 100 eggs: shiny at #56. (31/31/25/31/31/0)
It happened again! This is the Fifth time I get a shiny at <#100 using a couple with the same species. 3 times for this research (Gligar, mawile and now honedge). I want to believe that not using ditto increase your chances someway, I'm tired of shiny droughts, so I'll be using same species couples for the rest of this research. Some of you may say ditto doesn't affect, but my shiny trend says to me that something is happening there, not just random bad luck with dittos. Besides, 6ivs dittos are all hacked or generated by cheating, I really hate and don't trust that kind of pokemon :p