Gloom evolves into bellossom Sunkern evolves into sunflora Cottonee evolves into whimsicott Petillil evolves into lilligant
Source: http://bulbapedia.bulbagarden.net/wiki/Sun_Stone#Sun_Stone
Here's a list of Pokemon that evolve using a sun stone Sunkern --> Sunflora Gloom --> Bellossom Cottonee --> Whimsicott Petilil --> Lilligant
All of the above being at least part-Grass type
