Puree honeydew, watermelon and cantaloupe in a blender, in batches, until it turns to liquid . Add in lime juice. Chill overnight.
Pour Diet Sprite into a large pitcher and pour in the honeydew & cantaloupe puree. Do it slowly because it will bubble up due to the soda.
This makes about 8 cups. Since all ingredients are 0 SmartPoints on all 3 Plans, personally, I would not count a cup or two of this punch as any points. If you drink the entire amount in one sitting, that's a different story. So I would suggest that you count this the way you see fit.
Recipe by Dee Dee Does at https://deedeedoes.com/fantastic-weight-watchers-drink-recipes/