Can any one tell me more about unknown collector..and exactly it does ..it is asking me to give pawniard set ...

first of all, its not unknown collector, it is unown collector. and, if he is asking you to give him pawniard, then that does not mean that you have to go and find and catch a pawniard. if he asks you to give him pawniard set, then you have to go, find and catch unowns of letters p, a, w, n, i, a, r and d. make sure none of them is in your team and give it to him. if he asks you for another set, lets say, pikachu, then you have to find unowns of letter p, i, k, a, c, h, and u. hope this helps you.