Catch it as you would a normal Pokemon, they just have a lower Catch Rate.
If the legendary Pokemon is in a cave or dark area, use Dusk Balls and so forth.
You have to defeat the elite four then you can catch the legendary
you can't catch it because you already beaten the legendary
You can't catch shiny legendary Pokemon without cheats... sorry
You catch it.
you have to get more then 45 gym to catch legendary Pokemon! deoxys is a legendary Pokemon
You can catch Rotom.
you can catch as many legendary Pokemon but only once unless you have it on the computer
Yes, you can save the game before you catch it. but if you already saved it and the legendary is gone, then you can't catch it. if it is a Pokemon ranger game then you can catch it again
no
you first have to catch/defeat the legendary pokemon cobalion in mistralion cave you catch virizion in pinwheel forest
defeat all gyms,elite 4 and champion of that region to catch legendary pokemon
2 there catch rate is weak and they are easy to catch if you trap them