Though, I've learned a few tricks with MK during my time at GB that I might as well put here since we're not doing anything in Psych. >_>
Concerning mach tornado: If you stay on a person's shield with this long enough, they may lose patience and try and do something. if they do, you've got them. If they're not going to, you can usually tell about 3/4 through the tornado and back too far away for them to punish you.
Also, if you have someone in the tornado and want to keep them in, mashing b will help them DI out. So, to prevent them from getting out, keep the B presses down to about 3 per second; that way you keep them in and you get the most length possible out of tornado.
Concerning edge-guarding: If your opponent is offstage, you get offstage too. Don't worry about recovering, just be aware of how many jumps you have left and what you can do in relation to your distance from the ledge. Nair is a great killer at higher percents along with fair and dair. Fair should be abandoned with preference to dair at lower percents, however, because they use it's hitlag to DI upwards if they know what they're doing at all. Sweetspotting reverse shuttle loops (ala reverse dolphin slash) is extremely effective at any percent depending on their recovery abilities both as a character and as a player. The reasons you would reverse shuttle loop as opposed to the easier-to-pull-off normal shuttle loop hit are two fold: One, anytime you hit them during reverse shuttle loop knocks them back; Two, it's a lot less risky for recovery purposes since when you use shuttle loop you give up all other windows for recovery.
Concerning onstage combat: It's all mindgames when it comes to MK and the ground. If you manage to get grabs off (you should, he's insanely fast on the ground), always d-throw for combos. But don't always fair out of d-throw. If you find your opponent airdodges whenever you d-throw to avoid the obligatory fair, you have a chance do grab them again immediately after their air dodge. I'm sure it's very frustrating to have that happen to you, and an angry opponent is a weak one. Dash attack can lead into u-air -> combos with unerring consistency. Also, shuttle looping out of d-throw (from the air, of course) is very effective at higher percents.
That's about all I have off the top of my head. Ask me questions and I'll try to help out with them.
Concerning mach tornado: If you stay on a person's shield with this long enough, they may lose patience and try and do something. if they do, you've got them. If they're not going to, you can usually tell about 3/4 through the tornado and back too far away for them to punish you.
Also, if you have someone in the tornado and want to keep them in, mashing b will help them DI out. So, to prevent them from getting out, keep the B presses down to about 3 per second; that way you keep them in and you get the most length possible out of tornado.
Concerning edge-guarding: If your opponent is offstage, you get offstage too. Don't worry about recovering, just be aware of how many jumps you have left and what you can do in relation to your distance from the ledge. Nair is a great killer at higher percents along with fair and dair. Fair should be abandoned with preference to dair at lower percents, however, because they use it's hitlag to DI upwards if they know what they're doing at all. Sweetspotting reverse shuttle loops (ala reverse dolphin slash) is extremely effective at any percent depending on their recovery abilities both as a character and as a player. The reasons you would reverse shuttle loop as opposed to the easier-to-pull-off normal shuttle loop hit are two fold: One, anytime you hit them during reverse shuttle loop knocks them back; Two, it's a lot less risky for recovery purposes since when you use shuttle loop you give up all other windows for recovery.
Concerning onstage combat: It's all mindgames when it comes to MK and the ground. If you manage to get grabs off (you should, he's insanely fast on the ground), always d-throw for combos. But don't always fair out of d-throw. If you find your opponent airdodges whenever you d-throw to avoid the obligatory fair, you have a chance do grab them again immediately after their air dodge. I'm sure it's very frustrating to have that happen to you, and an angry opponent is a weak one. Dash attack can lead into u-air -> combos with unerring consistency. Also, shuttle looping out of d-throw (from the air, of course) is very effective at higher percents.
That's about all I have off the top of my head. Ask me questions and I'll try to help out with them.