After trying and (failing) all other solutions i came across, I found my own way to beat Hi-Score mode all the way through (7 wins). My *spam* solution works for the most part. Sometimes you have to improvise though. Especially vs. Hanzo (he can give you a hard time with his dissapear low slash move - don't know the correct name of it).
Pick Sogetsu, -> BUST, Beginners Class
Always start the fight with a back jump and
slash, now start spamming jump and D,DF,F +
- if your opponent is camping all the way on the other side spam the move while standing on the ground. If the enemy gets too close jump and
or jump off the side screen to the other side (but know that even if they get close they almost never jump slash or you are faster and hit them before they can slash through). In later fights your opponent will block 8 out of 10 moves but the chip damage (blocking) will get you the win (sometimes after timing out).
Good luck.
Video Solution:
Additional info from I AM CULLY: Using down, downright, right+Y on the ground is sometimes better when the opponent is at the complete opposite side of the screen. if they get a little bit closer, then I usually jumped first.
If you get Galford, this method absolutely will not work against him. I would suggest to die, then hit Restart. What this does is gives you a different set of opponents (whereas if you quit and just start again, it'll give you the same ones). I did this and as soon as I wasn't against Galford in my first 6, I won.