Ok then we have a different oppinion
Desynching a D/Fsmash in the right position(opponent at edge for example) , combined with for example waveshield(against a opponent who is shielding since that´s what we are discussing) or pure just spacing with Popo you get ALOT of control over the situation.
It´similar to when fox shines behind someone.
You can BOTH bait AND do the aggresive option(waveshield) at close to the same time, releasing A to attack, and react to what they do (if getting hit, be very fast and grab them in the hitstun), if they shield the fsmash, just grab them (possibly in shieldstun, not sure about that though, desynching dsmash after grab might make this safer but I´ve not tested it), if they roll, wavesmash.
Just realised the exact same thing can be achieved with shinegrab, but that´s more limited and less safe and less room for error.