User blog comment:Kogath/Monster Hunter XX Discussion/@comment-26995086-20170405121639/@comment-26421638-20170405214543

The clockwise Tail Swipe I'm 100% Sure that every Flying Wyvern can do that, even Astalos, although it does the tail swing only once before the electric Tail beam... I've seen all the Raths, Blos, Gravios and even Plesioth doing that.

Mizutsune cannot do a Straight Water Beam... 99% sure.

However, some things are extremely rare in MH, like Gravios doing Poison Gas, Bulldrome digging in 2nd Gen Games or an Alternative Mounting Animation for Kecha Wacha, but things like that may not happen every if you hunt an Monster more than 100 times, so everything can happen!