For compatibility with all hacks.

Set dash to whatever button you don't want to use ever again, ever.
AKA select.

Set item cancel to whatever button you use to run.
Works even better with project base gameplay.

Say dash/item cancel is B, jump is A, item switch is Y, & fire is X.
I can quickmorph using down+B.
Spinjump using B+A.
Backflip crouched.
Backflip directly from morph.
Metroids are easier to fight since item cancel every time I run.
Mockball is now easier to do.
More moves with less buttons.
Select can be programmed for beam switching or something more useful.
Or whatever button is most annoying to you.

Test on project base or the code from project base thread.
Controller.zip includes bin file for sprite replacement.

UPDATE:
Now includes a small piece of code to make samus always run. However, if
speedbooster is equipped, samus will always gain blue echoes. Your root button
(aka dash/select) now includes walk/speed limit, since switching hud items
was still annoying when you needed to run & grapple. (You can still hold cancel &
cycle through the hud to set up a one shot).

UPDATE:
If using with projectbase gameplay,
you can bluesuit backflip out of a speedboost mockball.
...
...
Still a whole button unused too.