Chicken pox
No, you can catch them only once per game.
No. You can only catch Rotom once.
You can only catch him once.
Because you only live once
In relic castle (once only)
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 not catch Pokemon you can only befriend them to use their poke-assists and field moves once.
you can catch as many legendary Pokemon but only once unless you have it on the computer
you can only find kyogre once
You are in luck. You can't catch gay diseases at all because there is no such thing as a gay disease.
Yes, turkeys can and will often catch diseases from chickens. This is why it is advised to keep turkeys and chickens separate, this way the turkeys cannot catch the disease from the chickens.