Put all the rums, the lime juice, Pernod, pineapple juice and Angostura bitters in a blender with ice and blitz for a few seconds. Or, shake well in a cocktail shaker filled with ice until the outside of the shaker is cold.
Pour the cocktail into a glass filled with ice cubes, then slowly drizzle over the grenadine. Garnish with mint, cocktail cherries and orange or pineapple wedges.