Thanks for the game.
Ok...I'm going to base my advice entirely off of what I know on X2, however I am aware that in Isuka there are two plains of combat, a foreground and a background, so you might want to figure out how to change between those. I think you can only hit someone if they are in the same plane as you.
If you are wanting a beginner friendly fighter to use, look for a guy named Sol - Badguy. He's fairly easy to use, and he does decent damage, and he has decent defence. You can use him to rush down the guy you're fighting and just try to link together some moves. When you do that, it's called a "gatling" combo. There are much more complicated combo's, using roman cancels and such, but those take a lot of practice to get used to.
If it's like in the last game, you have five attack buttons: Dust, Slash, Heavy Slash, and Kick.
You can use a standing dust attack to knock your opponet up in the air, and then jump after them and try to link together some attacks.
If you want movelists, I'm guessing that if you go on Gamefaqs and get one from X2, it will be mostly the same, thought hey probably changed some things.
I would recommend choosing a character and playing through arcade mode a few times and exploring in training mode, learning what the attacks do and how to use them. The thing about guilty gear is that you would need to play it for several weeks to get good at it, and several months to be great.
Also try to mix up your attacks. Attack high and low, and try to use a confusing combination of both so that they can't block all of your attacks.
If they kept the instant kill function, then you can press four attack buttons (other than dust), and initiate instant kill mode. In guilty gear, after entering this mode, you could do a quarter circle forward, quarter circle forward, heavy slash and instantly kill the opponet.
If you miss however, your tension bar will be gone, and it's often hard to hit them with it.
The tension bar can be used in a variety of ways. Special moves, a special shield thing, where you pull back on the controls and hold two attack buttons, and they can't hurt you.
Well, that's some general tips. Now all you gotta do is practice.
