It's from skillbooks i think, you'll get that later on in the game.

I don't want to make you confuse but I still gonna answer your question. In the future normal Sasuke's mystery will not gonna change but it become more powerful (ie : barrier stay even after used kirin) and yes he can chase with that ground chidori.

Similar thing in Ninja Exam. Occasionally 'wild' ninja setups in things like Sealed Ninja and Some other instances have slightly non-standard buffs and moves. You get used to it. Though Chojuro with Bloodthirsty can go jump off a cliff....

XD i totally agree with you about chojuro and bloodthirsty. i did it in sealed ninja a few times and once he go 7 normal attacks in a row. thats completely ridiculous XD.

one of my brilliant teammate decided to use multi clone + ao against dat chojuro AFTER I told him to drop clones....

Good thing my hinata can take 5 hits to the face....

I can't quite recall right now, but does the chojuro and some demon zabuza in exam gain 2 extra attack per kill or something? or does chujuro gain +1 for each kill made as opposed to each time he kills (so if he kills 3 in one hit, +3?) In any case, for some reason I think they keep going even after being stopped twice....

Chase skill with ground chidori? So the Kirin mystery stays, except it'll become permanent as a barrier skill, thus reducing one turn for use of Kirin (basically almost becomes like Playboy Sasuke who can instantly use Kirin without placing barrier and waiting for a turn to use the Kirin attack)...
And the AI Sasuke that uses Ground Chidori as a mystery will become a weaker chase skill for a default player Sasuke?