When you have a rhythm containing more than one kind of note, you'll see the Shift/Randomize option become visible in the Metronome menu.
In there, you can shift and randomize rhythms, sounds, and accents (depending on if you have sounds and accents assigned).
You can also tap the padlock button to lock one of those features to the main screen in order to be able to automate the action every x reps.
NOTE: The options in the Shift/Randomize menu are dependent on what is programmed into the sequencer(s). You won't see the Accents tab if there are no accents in your pattern. Also, you won't see the "Shuffle Accent Groups" option unless sounds are entered for a full cycle of the rhythm.
Watch the videos to learn more.
Shifting and Randomizing Rhythms
Randomizing & Shifting Sounds
Random Melody Generator
This video explains how you can shuffle sounds from a much larger selection than you can fit into a single bar.
Randomize & Shift Accents