Problems with the Utira city Drilbur trade

My game crashes right before it opens up the screen that let's you chose the dragon-type Pokemon to trade for Drilbur in Utira city. It lets me talk to the hiker without crashing the game as long as I don't have a dragon type in my party, so I'm pretty sure it has to do with opening up the Pokemon selection screen. I've already tried using various dragon types, but all of them crash the game.