C0rvus
Pro Hands Catcher
Diddy I'll admit is likely close to even, but it's an uphill battle. I don't have enough Cloud experience to really say, since I generally opt for Corrin in that MU.
Pretty much any character with explosive or consistent kill power can be difficult for Lucario. (See Hikaru vs Tsu at Civil War. When DK is ending your stocks before you get to high aura, it's hard to close stocks yourself.)
Pretty much any character with explosive or consistent kill power can be difficult for Lucario. (See Hikaru vs Tsu at Civil War. When DK is ending your stocks before you get to high aura, it's hard to close stocks yourself.)