Try the grass on Route 117 outside of Mauville City. Roselia has about a 30% catch rate there.
I don't think Roselia evolves in Pokemon Sapphire, but i do know that it evolves in Pokemon Diamond and Pearl. If I'm wrong please do tell ASAP. Thank You.
Route 117
Roselia can be found only in Ruby/Sapphire, on Route 117. Unfortunately you can't. Roselia can't be caught in the wild in Emerald. With that being said, it may be possible in a copy of Ruby or Sapphire, and you could trade it over. Otherwise, you're pretty much sunk.
machop,poocheyana,magicarp,garados,roselia,pikachu,
On the route west from mauville city look for Roselia in the grass it's rare to find though.
you cant catch roselia in emerald, but I'm pretty sure you can catch it in Sapphire, so just trade it over
You have to trade with Ruby or Sapphire to get a Roselia.
You have to trade from... Ruby: Meditite, Medicham, Roselia, Zangoose Sapphire: Meditite, Medicham, Roselia, Lunatone Colosseum: Meditite, Medicham XD: Meditite, Medicham, Roselia, Zangoose, Lunatone These are only the missing Hoenn Pokemon.
Surskit, Masquerain, Mawile, Tropius, Illumise, and Roselia all learn Sweet Scent.
there are many MANY Pokemon that can use the hm flash in Pokemon sapphire. the following Pokemon can: grovile( treeko),kirlia(ralts)shroomish, eletrike, Roselia, plusle, munun, magnemite, voltorb and many more
You can't evolve roselia. Its evolution was made in gen 4.
In Pokemon Sapphire, Latios can be found in Southern Island.