After you beat the E4 go downstairs, your mom will ask you about the colour of a Pokemon on TV. If you choose Blue you can find Latios roaming Hoenn.
no but you can get in emerald or ruby not sapphire
You don't.
you cant on emerald I'm not sure about any others i hope that helps
No.
Of course it does
No,but i seemed to get them near or in water
i know how to get nearly every Pokemon without a cheating device. do you know how to get Deoxis on emerald Or is there a way to get Darkrai on diamond without cheats?
No, you either pick one or the other.
BY HAVING THE MYSTIC SHINY POKEMON. WHICH IS ONLY OBTAINABLE IN POKEMON FRIGO RETURNS. WHEN YOU GET IT JUST TRADE IT TO POKEMON EMERALD.
you can't without a eon ticket and that event has already passed i do not recommend action replay or game shark or ANY KINDS OF CHEATS
You either cheat (sorry) or you just keep winning the poke ID lottery in the mall.
I am sorry but I can only answer the WHICH in your question. From my knowledge you can get the pokemons: Kyogre, Groudon, Raquaza and both the lati's(Latios and Latias) if you have the Eon ticket if not then only one of them you get to choose(I recommend Latios it looks wayyyy cooler!!) These are the pokemons I think you can get without using gmaeshark codes or any other types of cheats.