Have a Ditto and breed with whatever Pokemon you please at the daycare. You can't breed Legendaries. If you don't have a ditto, search which compatible Pokemon is best to breed with the Pokemon you want.
Hatch? No. No legendary Pokemon can be bred in any Pokemon version. You can catch Kyogre in Sapphire though ;)
Pokemon Ruby has Pokemon that Pokemon Sapphire does not and Pokemon Sapphire has Pokemon that Pokemon Ruby does not.
There is no Pokemon mansion in sapphire.
He is not in Pokemon: Sapphire. You will not be able to find him. He is in Pokemon: Diamond, Pokemon: Pearl, and Pokemon: Platinum. You will definitely have trouble finding him in Pokemon: Sapphire.
Evee is not availiable in Pokemon Sapphire.
Any Pokemon in sapphire but you have to migrate
You cannot get Regigas in Pokemon Sapphire as it is from the next generation of Pokemon
sinnoh Pokemon won't appear in Sapphire version!
All Pokemon in Pokemon sapphire can breed. Except for all legendaries.
Not in sapphire.
There is not a bike voucher in Pokemon sapphire
Almost all pokemon with evolutions can be bred. Legendaries can not though.