Stone Edge was introduced in Generation IV, so therefore, it isn't in Pokemon Ruby.
How to go to verdanturf town in omega ruby
Mewtwo is unavailable in Omega Ruby and has to be transferred from another game
i think they can be bought somewhere from wut i rember ( i completed omega ruby)
You can find Water Stones in Pokemon Omega Ruby and Alpha Sapphire at the museum.
Seedot can be found in Route 102.
No, you will need to trade for them or transfer them via Pokemon Bank to get them in Pokemon Omega Ruby and Alpha Sapphire.
You can catch Nincada in Pokemon Omega Ruby when in the shed.
In Mt. Ember.
You can catch Carvanha in Pokemon Omega Ruby by sinking his ship.
You can catch Wingull in Pokemon Omega Ruby as it flies in the sky.