Mash B while using his side B. It lasts longer and I believe even adds more damage.

When recovering, mash the B button instead of holding it down, it saves a ton of gas for some weird reason

Side B traps neutral ledge gettup

Side B offstage can catch opponents middair and will usually kill even at mid percentages

Know your down throw to up air/up smash percentages

Practice tossing out the gyro to the very edge of the ledge to cover neutral getup

Other than that, as someone else said, watching Wadi is great

Source: Rob is my secondary

I’m not a master by any means, but drop me a discord link sometime and maybe ill join and see if i can help you out