simply when doing a ground pound mash the A button as fast as possible.

Why is this helpful? Hitting an opponent with a groundpound is one of the fastest ways of filling the smash meter, so being able to hit three can guarantee the meter to be full.

When to use this tech? Either when performing an air combo to an opponent, or when you need to reach the floor as fast as possible, it should be known that in stages such as the Enchanted Forest or Shrek's Swamp that being able to move down 1 or 2 branch levels can really make a difference on your time when performing this tech.

Any other tips? I would suggest trying it out with multiple characters, personally I found it to be most useful to use after performing 2 or more neutral air strikes with Puss n Boots. Plus this is a rather undiscovered game so there may be more useful tech to be researched.

This pages Discord can show you a video example https://discord.com/channels/724846377078882334/724846984753709058/820470595136913448