you go to trade corner, select the button that says "trader reviews"
https://www.pokecommunity.com/forumdisplay.php?f=270
then you just click on the one that says the person you traded with's name one it
https://www.pokecommunity.com/forumdisplay.php?f=270
then you just click on the one that says the person you traded with's name one it