1. Crossing him up with Fair over his shield is good
For ex. Fair at head level > and instead of following up with dair or nair, fast fall behind his shield and grab him, or wait for his spotdodge then punish.
Spot doding when someone is standing behind you is a really bad habit that most people have, but if they're smart the might SH bair.
2. Run up to his shield and roll behind him
Idk why it works so well lol but it throws them off.
3. Whenever the run up to you, there's an 80% chance that they are going to shield, just grab them and throw them away. From that point it becomes a game of R/P/S whenever the want to grab you.
4. Charge Fsmash.
D3's get off on Powershielding everything and grabbing it, just charge for a second longer before you let it go.
5. Jab, it's really good against grabbers/spotdodgers. Not the full jab combo, just the first 2.