No, you can catch them only once per game.
You can only catch him once.
No. You can only catch Rotom once.
Because you only live once
infectious diseases (those with bacterial or virus, or prion) you can also "catch" chemical based diseases such as contamination burns if you come into contact with someone with the chemicals on them.
In relic castle (once only)
You are in luck. You can't catch gay diseases at all because there is no such thing as a gay disease.
you can only catch it once you know surf. come back to union cave once you know it and go right down to the bottom and you'll find lapras (only on fridays)
You can only catch Lugia once, but you have two chances to cat it. The first time in the story and later on. So if you catch Lugia once already, he won't be there the second time.
you can catch as many legendary Pokemon but only once unless you have it on the computer
You can not catch Pokemon you can only befriend them to use their poke-assists and field moves once.
you can only find kyogre once