Phione is unobtainable in the wild in Pokemon Omega Ruby and Alpha Sapphire and thus cannot be captured.
However don't let that fool you, you can indeed get a Phione in your version of Pokemon Omega Ruby/Alpha Sapphire by either;
- Using Poke Transporter to transfer one from a Generation V game (Black, White, Black 2, White 2);
- Transferring one over from another Generation VI cartridge;
- Breeding a Manaphy with a Ditto;
- Obtaining one from a future, unannounced event;
- Or by cheating/hacking (although this is unadvised by most players).
Just to add that's an awesome username you've got there.