Okay so I've noticed a lot of newcomers to the game are having trouble against Sasuke. Here I'm going to explain how to fight the standard WiFi Spammers who do j.b AAAAA over and over again as well as the ones who just abuse j.b too.
First off Sasuke is a pretty scrub friendly character, not as scrub friendly as Hiruko but still pretty scrub friendly thanks to his free teleport with j.b. At first it may seem like this is one of those stupid tactics that you're never going to get past without having to take tons of damage only to then hit him and have him KnJ and start all over, right? Well that's pretty damn wrong. This tactic is really easy to get around and punish. Despite all this Sasuke is a solid Mid Tier character that requires a lot of patience and mind games thanks to his lack of good mix-up options and a lot of unsafe strings on block.
This is how you beat it. Simply walk backward. That's right, just walk backward. Walking backward is an auto guard while your facing the opponent but if you're opponent somehow appears behind you it turns you around to face them and goes back to guarding. This is the key to defeating Sasuke's j.b. Once you're turned around there's a few things you can do which I will list now.
1. Attack Sasuke with a B string.
Depending on what the Sasuke does you can simply attack him after he re-appears. If they try and use the A (Snake Sword) on you it won't matter because Sasuke' A is too slow coming out to your jab will connect with him before the sword comes over Sasuke's head, granted you have a good frame jab one like Naruto or Lee's.
2. Side step and punish after you've turned around.
If the Sasuke tries an A or B string you also have the option of side stepping away and punishing him with anything you choose.
3. Take AA or BB on block then side step.
The third hit in both Sasuke's A and B Strings are uppercuts that are EXTREMELY slow. These are both slow that as soon as the second hit connects on your guard you can mash side step and evade the third attack then punish Sasuke with anything you want, especially if they use the AAA string since the sword has tremendous cool down time.
4. Attack Sasuke with a B string after taking BB on block.
Because his Third B move in Sasuke's BBB is so slow you can also simply attack him after taking the second hit of B on block. Naruto, for example, can A or B before Sasuke's third B comes out.
5. Use the 'Paper Bomb Stance' to auto turn and block upon Sasuke re-appearing.
When Sasuke ports behind you, you can also press L+R after he disappears and your character will auto turn to face him as he reappears. You can then immediately punish by throwing a paper bomb (online a paper bomb hit if the opponent isn't guarding means auto stage transition) or just letting go of L and R and go back go guarding.
This is basically how to deal with the standard WiFi Sasuke but be aware you may come across a halfway decent or good one. Sasuke's main thing is confusing his opponent by continually j.b porting around to create an opening in his opponents missed punish. Since this is WiFi you shouldn't have to worry too much about Y-Cancel's since they're difficult online and Sasuke's are very frame strict meaning most won't be getting them off on you online.
Sasuke can Y-Cancel the following.
The third A in both these strings and the second B in the Back B string launch the opponent into the air so both are able to be canceled. Sasuke can then follow up with another B string or a well timed A string.
Sasuke's j.A, Katon: Housenka no Jutsu (Fire Style: Phoenix Flower Jutsu), is also pretty amazing because of the range, but it takes one bar of Sasuke's Chakra. You can dash at then side step this and catch Sasuke before he lands since he floats slowly down to the ground, especially if they use it after both of his mid-air jumps. Sasuke can SHj.A and follow up into an A String, if the j.A hits you expect to take some serious damage.
I hope this helps some of you annoyed by this character. I do this all the time and beat these types Sasuke's.