These 'mons include Dialga, Giratina, Groudon, Kyogre, Kyurem (Both Forms), Palkia, Rayquaza (and Mega), Reshiram, Xerneas, Yveltal and Zekrom.
Only Choice Scarf Kyogre is very popular, the rest aren't. Most Xerneas use Power Herb, and most Yveltal has Max Airstream to raise its speed. But what about the rest?
Edit: I am asking if these 'mons are viable to run a Choice Scarf to outspeed Calyrex-Shadow, Zacian-C, Eternatus, Ultra-Necrozma, Rayquaza-Mega etc and potentially OHKO them. If they didn't, then their scarf becomes waste. Half of the above mentioned 'mons are not viable, but if they run Scarf, would they be viable?