Delay in controls and unresponsiveness?

I am far from the best player but I'd like to think that I'm decent, so when I see someone on youtube do a fancy combo I wanna try that too, but I can't do it... I can't figure out the recovery for all characters and I don't know what attack sends my characters into "non-recovery" where I fall helplessly without anyway to redeem myself but...

I know that I should be able to do this, the quick running back and forth spamming the player "RedRiot" is doing in this gif. https://i.imgur.com/k6EgjkK.gifv
But when I try the same when I'm playing and no matter who I'm playing as, I can't do it. My characters awkwardly lurch from left to right, not turning around like they're supposed to.
I've tried with the Pro controller and the Joy Cons, no luck. Are they intentionally made to be weird so the Gamecube controllers sell more, is my Switch broken somehow, or am I missing something in the game's controls?