Combine the mango nectar, guava nectar, pineapple juice, cream of coconut, lime juice, and rum in a large pitcher, and mix well.
Combine 1 cup punch and 2 cups ice cubes in a blender and blend until smooth and thick. Pour into glasses. Repeat with remaining punch and ice cubes in batches. Garnish with the fresh pineapple or lime wedges and serve.