Legendaries are the most difficult to capture, weaken them to red hp then inflict a status problem on them like sleep or paralyze then continually throw ultra balls if the Pokemon is a water type like kyogre try using net balls, if you owned this Pokemon before use a repeat ball.
The best say to catch legendaries is to lower its health down to red and to either paralyze it or put it to sleep. Use Ultra Balls to try and catch them.
The legendaries you can catch in Pokemon Ruby without trading or going to an event are Groundon, Rayquaza, Latios, Regice, Regirock, and Registeel.
Latios, groudon, Rayquaza, Regice, regirock, registeel, they are the legendaries you catch int he game without cheating or trading
catch them
All The Shiney Pokemon You Can Get In Pokemon Ruby Are All The Pokemon You Can Get in Ruby Any Pokemon Can Be Shiney Even Starters and Legendaries. So There Are 200 Shiney Pokemon You Can Get In Pokemon Ruby.
you cant catch a man in Pokemon ruby
no you can catch a charizard in pokemon ruby you can get it as a kanto starter
you can't catch seviper on Pokemon ruby (Pokemon sapphire only)
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go to this page http://www.serebii.net/diamondpearl/legendaries.shtml this page has all the legendaries you can normally catch in in Pokemon diamond/pearl all other legendaries you have to transfer from a 3rd generation game
arceus
Not including the legendaries and special pokemon ( ones that you can only catch once ) feebas is the hardest and rarest pokemon to catch
raikou cannot be caught on Pokemon ruby