Gold medal for catching 300 big magikarps

There is no reward for completing the medals.

There is only one use:
Make a screenshot of your medal and link it to your account in a social network, so you will certainly draw attention of many attractive women. :-)

Earnest:
No, there is no use for this medal.

No reward, they should have given some sort of Exp for completing them like the other medals give catch bonus, but nope. not a damn thing, just for show.