How to get the mythical ! ? unkowns in pokemon platinum

The distinguished Zekisham spake:To catch them,it's simple.Only do these steps:

1)Catch all normal unkowns

2)Go to the cave near at the place where you get Giratina's orb(I think it's named Gorgeous Orb[Giratina's Orb],but I don't remember it...Much time without playing Platinum...)

3)There is a person in the cave.He has opened a way to go deeper in the cave.Take this way.

4)Here you are!Now you can catch these mythical unkowns!(! and?).You can also take an item if you go even deeper.

I hope I helped you...

thinks