I find Pika's up-B really hard to control without the octagonal gate that's on the gamecube controllers, but missing on the Switch Pro Controller. But I much prefer the button layout and triggers of the modern controllers. So it's annoying. I used the Classic Controller Pro for smash4 which has both, except it puts the control-stick in a weird spot (where the Dpad should be instead) which makes it harder to control, and also of course uses the Wiimote with its wifi lag.
I would love a best-of-all-worlds controller which to me would just be the Switch Pro Controller but with an octagonal gate, and also make sure that the driver gives it no worse lag than GC controller (there's rumours it might sometimes be at frame-1 disadvantage, ugh).
But now that you mention it -- would it be possible to notch at 15degrees to make for perfect quick-attack angles? That would be awesome. Like how some people would file little notches into their GC controllers to help with some things, maybe we could do that to assist Pika quick-attack. If that would even be legal.