Okay I know there is no Unchained Ninja... but if I multi-class Unchained Ninja and Monk it seems to me you can get a pretty fun build.
Ideas:
With three levels of rogue you can get a free weapon finesse and dex to damage for your unarmed strikes! with flurry and a near full attack that is worth the dip. Plus better skills, 2d6 sneak attack damage and a rogue talent (lots of good options here) Plus most of the rogue archetypes still work so you might even be able to get a good archetype so you don't double up evasion.
Pepper in levels of monk maybe another couple levels of rogue if you have something you want.
picking up monastic legacy and a monk robe to mitigate your unarmed damage loss.
Now my question is: "Unchained Rogue says I can take still take Ninja trick as a rogue talent, but it doesn't say I can take ki pool, but if I have a ki pool from monk will I be able to power a ninja trick (say vanishing trick) with my monk ki. I would say yes because "ki is ki" but I'd love someone to way in.
Anyway I am going to keep looking into this possible new assassin lot of potential!
also why not extra Ki as a 6th level+ monk bonus feat?
Ki has always been ki.
Thank you Chess.
Another question:
If I used Elbow smash while in a situation granting sneak attack would that allow Elbow smash to deal sneak attack damage (even if i would have to be nonlethal?)
Yes, it's another attack so if it connects it's a carrier of sneak attack