RAYQUAZA
no you can, you most catch it in Pokemon emerald
Just catch the most Pokemon you can ;)
Yes there are plenty of kanto and mostly johto Pokemon you can find in emerald most of them can be hunted down in the safari zone.
a masterball cause it is the most powerfull pokeball with 100% catch rate to any pokemon
You can't possibly find all the Pokemon in emerald there are some you can't get like surskit. you can get most of the the hoenn Pokemon in emerald and some of the johto and kanto. But other than that you will need to trade the Pokemon over to you're current game.
Kinda. But most super rare pokemon you would want to catch U could not get without getting a Nintendo event ticket.
rayquaza
The strongest Pokemon on Pokemon emerald would probley be raquaza
You can capture wailmer in ruby, sapphire and emerald on most routes where water is you can find either by using a rod or by using surf.
Safari Zones are places where you pay to catch Pokemon. Most games have a Safari Zone or something similar. Safari Zones almost always have at least one species of rare Pokemon that you can't catch anywhere else, such as Chansey, Drapion, or Octillery.
Kyogre.
There is a way but it is hard.(this is only possible if you mean only Pokemon from 1 region) First you must catch the most Pokemon that you can find (no doubles) and then you must trade from other games to get the Pokemon that you can't catch in your version