The catching system is based entirely on luck. Before you even attempt to catch a pokemon though, you MUST weaken it. You CANNOT catch a pokemon that is a higher level than yours. If you roll a pokemon it is ALWAYS the same level as your highest level pokemon. You cannot catch already evolved pokemon, those pokemon could have eggs or babies waiting for them back at the den!
Once your pokemon hit level 30, you must roll a die to determine it's level when you catch it. The die ranges from 1-30, but when you fight the pokemon it's the same level as your highest level pokemon.
[roll= "Pokeball"] [/ roll]
[roll= "Greatball"] [/ roll]
[roll= "Ultraball"] [/ roll]
[roll= "Level"] [/ roll]