Thats the good thing about perfect shielding being so easy in this game. If the marth is dashing towards us, they will prlly forward B. Thats when you shield until the last hit. They could try and mix it up on you, with grabbing afterward the first dancing blade hit, and thats pretty hard to guess. But usually they wont. Also, you could make it a guessing game and just nair out of shield. Also, full hops with bombs, and landing with invinci bombs would help alot. The main problem is his fair. Well, for me it is. Thats when zair comes into play. Usually I use bomb to zair, while retreating, so,
1. they shield everything, but thats when we juggle the bomb off their shield with different arials
2. They get hit by the zair and bomb, and we follow up
3. They roll behind us and begin to pressure us again.
lol, actually, there's plenty of options in that situation that I dont feel like explaining xD..
But if TL gets Marth behind him, we are pretty safe if we mix it up properly and space extremely well.