Right now, MK's most useful throws are his up-throw and his down-throw. His up-throw does one percent more damage and can be used to KO. His down-throw, however, has a more strategic use.
When you down-throw, you can react to your opponent's DI and create an opportunity for more hits.
DI Away: Dash-attack into up-tilt is the standard follow up here. If the enemy tries to air dodge out, they'll land on the dash-attack, which is good for you. If they keep waiting and they tech behind you, they can get out.
In this case, you can do a few things. You can dash at them, jump to stop your dash, and start a Mach Tornado. Use the speed of the tornado to chase them down and get some more percent. You also can pop them up onto platforms where you'll have an easy time chasing them.
The other trick is to dash in and shield to cancel your dash. Drop your shield, and follow their tech with another grab, a smash, or dash attack. The shield-drop lets you adjust for whichever way they choose to tech.
DI Towards: In this case, you can usually just land a forward-air. This is great, except that it doesn't do very much damage. I prefer to stay still and wait for them to respond (with an aerial or a dodge) and then grab them right as they hit the ground. This lets you repeat the down-throw, and also irritates them. Use the grab attack to help reset your damage decay during this string, and you'll do a lot for helping your KOs.
If they catch on to this though, they may just jump away and you won't get anything. That's why it's important to mix this up with forward-air or dashing up-smash.
No DI: I treat this the same as DI'ing towards me, except they're a little farther away. In this case I walk towards them a bit.
After any down-throw you can almost always chase with Mach Tornado. This is a good option if you want to a) annoy them or b) reset the damage on other moves. It's also an easy counter to air dodging and it beats a lot of aerials, so it's usually a safe follow-up.
Remember, your follow-ups are almost never guaranteed. You usually have to guess what the enemy will do if you want to keep hitting them.
When you down-throw, you can react to your opponent's DI and create an opportunity for more hits.
DI Away: Dash-attack into up-tilt is the standard follow up here. If the enemy tries to air dodge out, they'll land on the dash-attack, which is good for you. If they keep waiting and they tech behind you, they can get out.
In this case, you can do a few things. You can dash at them, jump to stop your dash, and start a Mach Tornado. Use the speed of the tornado to chase them down and get some more percent. You also can pop them up onto platforms where you'll have an easy time chasing them.
The other trick is to dash in and shield to cancel your dash. Drop your shield, and follow their tech with another grab, a smash, or dash attack. The shield-drop lets you adjust for whichever way they choose to tech.
DI Towards: In this case, you can usually just land a forward-air. This is great, except that it doesn't do very much damage. I prefer to stay still and wait for them to respond (with an aerial or a dodge) and then grab them right as they hit the ground. This lets you repeat the down-throw, and also irritates them. Use the grab attack to help reset your damage decay during this string, and you'll do a lot for helping your KOs.
If they catch on to this though, they may just jump away and you won't get anything. That's why it's important to mix this up with forward-air or dashing up-smash.
No DI: I treat this the same as DI'ing towards me, except they're a little farther away. In this case I walk towards them a bit.
After any down-throw you can almost always chase with Mach Tornado. This is a good option if you want to a) annoy them or b) reset the damage on other moves. It's also an easy counter to air dodging and it beats a lot of aerials, so it's usually a safe follow-up.
Remember, your follow-ups are almost never guaranteed. You usually have to guess what the enemy will do if you want to keep hitting them.