AlMoStLeGeNdArY
Smash Hero
dtilt will clash with fireballs so you don't always have to shield them. If theyre approaching with SH aerials as Mario you should crouch as rosalina. That's partly the reason why I mention dtilt. If you lower your hit box it becomes more difficult for Mario to approach you. If you can read his approach you can Usmash. Then theres dash away pivot ftilt which is pretty good.
With shulk you must understand his moves a little bit then you should be fine it's not as difficult as it seems. I believe his nair starts up on 13 frames and hits behind him first. So if he's using nair to attempt to wall you should be able to tell if his back his turned or not. You have more time to challenge the move with your own nair if his back isn't turned to you and you can react to it. Then you need to take into account that nothing he does is safe on shield with the except of Monado canceled aerials and aerials in buster when spaced properly. If he's doing rising nairs at you punish that crap. He's going to attempt to use the first hit of nair as pressure which means RAR approaches from him which makes his approaches easier to anticipate and deal with..
With shulk you must understand his moves a little bit then you should be fine it's not as difficult as it seems. I believe his nair starts up on 13 frames and hits behind him first. So if he's using nair to attempt to wall you should be able to tell if his back his turned or not. You have more time to challenge the move with your own nair if his back isn't turned to you and you can react to it. Then you need to take into account that nothing he does is safe on shield with the except of Monado canceled aerials and aerials in buster when spaced properly. If he's doing rising nairs at you punish that crap. He's going to attempt to use the first hit of nair as pressure which means RAR approaches from him which makes his approaches easier to anticipate and deal with..