Go to Mossdeep city , then go to the space station, talk to the sailor, and he will give you a sunstone.
Chat with our AI personalities
Get a Gloom and use a Sun Stone on it.
you can only trade a sun stone with someone who has fire red, leaf green, or emerald.
To evolve certain pokemon. Eg a gloom into a bellossom
it doesn't evolve by itself, you need a leaf stone or a sun stone... the leaf stone will get you a vileplume, and the sun stone will give you a bellosom.
gloom evolves into a vileplume with a leaf stone and into bellossom with a sun stone