If they are not level 100, they have the ability to level up and learn moves that you don't want your Pokemon to know. My advice is that you keep your Pokemon with you. You can keep a Ditto in there if you want because Ditto cannot learn any other moves beside Transform.
It all depends on how you train your pokemon, what moves you teach them, and how you much you care about them. :D
look up on Bulbapedia what egg moves that pokemon can learn, then teach the move to the father, and leave him and a suitable female pokemon in the day care. The pokemon will hatch with the egg move.
It could have the same moves. Why do you care are you nurse joy?
yes but you don't know what moves the day care lady will change
no, sadly. The day care man can only raise one pokemon at a time
You send it to day care until it goes up 12 levels.
actually yes it is the Pokemon evolve and learn new moves
You must have a female starter. Then, put it in the Day-Care with another Pokemon in its Egg Group(Example: F. TREECKO + M. ROSELIA = TREECKO EGG) You can use this to make Pokemon with special moves called Egg Moves.
By battling other pokemon, use rare candy, or by putting the in the day care for a while.(note: if you leave a pokemon in the daycare for a while they may forget some moves you taught them)
if you mean nature, as in: what its for then a day care centre is so you can put your Pokemon in with the guy and he trains them so their level gets higher but they cant learn moves i wouldn't advise putting your Pokemon in there unless your desperate for levels.
Nothing too special, I think. They will level up and if there's two, they may have an egg. The carers will also teach them new moves as they level, so be careful if your Pokemon have moves you really want to keep.
Battle othe people or leave them in the day care. However, you can't choose what moves they will forget or learn and they won't evolve.