Byleth vs Donkey Kong

Take that monkey to heaven.

The Double Up-Special 0-death can be di’d btw

As Alpharad says, you are the distance demon. Use moves like fsmash and fair to keep your distance. If DK cargo throws and sets for the fair spike, get lower than him and up special to watch him fall.

up b-> nair-> upb->nair->upb->nair.

Don't try to do the zero to death. Most DK players expect beginning Byleths to attempt this, and will airdodge out of the combo. Use your range to snuff out approaches.