Short Macro Pin

You'll short the macro pin GPIO 22 to ground with a short length of wire (or a jumper shunt if you're fancy, since pin 22 happens to be right next to a ground pin).

You configured the macro to run as long as the "button" is held, so this will stay permanently connected.

Ball Prep

Use cutters or a hobby knife to make an opening in the Pokéball for the USB cable.

The ball I had happened to have a coin slot for use as a piggy bank, but the slot wasn't big enough so made the slot a bit bigger.

This will vary depending on the ball you use, or you can add an appropriate opening to a 3D model before printing.

Catch the Pico!

You probably want to throw your Pokéball into battle to catch the Pico (me too!) but you probably should gently place the Pico inside the ball, plug in the USB cable, then close the Pokéball.

Plug it In

Start up your Switch, launch your Pokémon game of choice (Shield shown here), and play the game as usual. 

To run the Auto Spin Macro, simply plug the Pokéball into the Switch's USB-C port. The Pico powers on and immediately begins to run the macro on loop until you unplug it.