@
AlmightySo
Some more details:
Basically you have a guessing&reacting game in neutral.
MK often has slight advantages because he has a enormous boost grab and great dashdancing, so both advantages for your approach game. His shield size can make anti-approaching a bit risky, together with the fact he can't wall out opponents simply.
You don't have a weapon as the shine though, and your aerials aren't safe by timing...
That leads to the conclusion you generally want to approach, but a bit carefully.
As @
victinivcreate1 already mentioned, this means you want to rely on your movement options, while mainly threatening boost grab, JC grab, nair and down-tilt. If they like to shield, go for boost grabs more often (bigger range) while you should rather JC grab if you are not so sure because its less punishable. You can also threaten a boost grab from a range where they can't punish, bait out there spot dodge and grab after that. An underrated/underused tool is also to dash behind them if they like to shield/spot dodge/roll because any attack OoS will need longer (shieldgrab isn't avialable now).
A tool your opponent can use is a ground move to anti-approach your movement&grab game. Another issue can be that grabs will often lose to a WD back OoS. Because of this, you also need other moves in neutral. I mainly recommend nair, it is fast and together with your horizontal movement from the full jump/short hop it should reach your opponent in time. If you space it "normally" it is easily shieldgrabbable though. You have three options to make your nair safe:
Full jump autoland (on platform nair), which does only require a platform and is really tough to deal with, WD back OoS is your opponents hope here because it has not that much horizontal momentum. You can fall through the platform very quick again and try to land -> grab or do a nair on the back of their shield.
Then crossup nair (dash shorthop nair) beats WD OoS because it sticks out a hitbox over much horizontal distance. To make it safe on shield, you need to start it when close to your opponent (so you will crossup) which makes it vulnerable to an early aerial OoS. Well-timed spot dodges are also a problem, without the shieldstun the bair OoS does well for many characters.
The fadeaway nair (press back in the last jumpsquat frame, nair, hold back) also needs to be started close so it can lose to early aerials OoS. If they react right they can WD back OoS which gives you just a little pressure advantage, if they stay in shield you are very close to a guaranteed grab.
A last trick about nair shield pressure is to fake out the "normally" spaced nair on shield while not doing the nair, they will shield to do a shieldgrab and you can land and grab them, a socalled tomahawk grab. Start mixing in normally spaced nairs now because they will think you won't put out a hitbox to get the faster landing.
There are two more cases to review: They want to pressure you... You have many possibilities to stop their running in, the one I prefer is dash in SHFFL fadeaway fair (do it as the nair just with a fair) because fair has multiple hitboxes catching different timing possibilities. If you are forced in your shield you still have shieldgrab, nair OoS, up-B OoS, WD OoS, and even Cape OoS. As general rule it is pretty hard to go aggressive enough to force a non-passive MK into his shield without having to take huge risks.
The last thing (if they are mobile characters too probably the best) is too also use movement to bait out and punish moves. Here my advice is to not fall into predictable patterns, not throw out slow moves and if you throw any moves out, only if you are convinced they will hit. You need to be on point with your movement, too. The best moves to "catch them" is f-tilt (learning pivot and runcancel f-tilt helps here really) when they end up being close more often, if they stay more spaced but still in d-tilt range this is your number one move, nair is multifunctional and retreating fairs if you want to read an offensive tendency, and grabs if they shield or stay where they are too often. If they throw out moves always shield when you have gone in the most and quickly wavedash back to continue the movement game.
. Also, his wavedash definitely feels longer.
