You can find Gloom in the patch of grass by the resort area.
sunkern or gloom sunkern into sunflora and gloom into bellosom
You can evolve Sunkern or Gloom with a sun stone. Gloom to Bellossom. Sunkern to Sunflora.
with a sunstone get one underground
to get bellossom in Pokemon pearl, first get a gloom. then use a sun stone on glooom and it will evolve to belossom.
gloom to bellosom sunkurn to sunflora Sunkern and Gloom are the ones who evolve using a Sun Stone.
some Pokemon you use a leafstone on are nuzleaf, execute,gloom, and victrebell
Gloom and Weepinbell.I think there are some more Pokemon that evole with a leaf stone but I forgot....
If you use a sunstone on a Gloom it will evolve into Bellossom, but if you use a leaf stone on a Gloom it evolves into Vileplume. I added some links incase you want info on these pokemon :)
As of Pokémon Pearl, there are only two Pokémon that can evolve with the Sun Stone item, the first Pokémon that can evolve with it is Gloom and it will evolve into Bellossom and the second Pokémon that it will evolve is Sunkern and it will evolve it into Sunflora.
The item sun stone evolves: Gloom - Bellossom Sunkern - Sunflora
Gloom is a Grass-Poison type Pokemon.
In Pokemon Diamond, Pearl, and Platinum, Gloom, Weepinbell, Exeggcute, and Nuzleaf all evolve from using the Leaf Stone.