Grabbing EndQuote's last mon.
EDIT: Take any one of the Tyrogue evolutions (preferably female but I understand if you don't want to grind for it) and name it Sejuani. Sejuani is inspired by this League of Legends character
, who apparently spend years training absolutely naked in freezing blizzards. Cool stuff, right? Well, you seem to have a bit of an Ice weakness, and Sejuani has trained her entire life to fight in the freezing cold. Obviously, you'll need to have her solo Pryce to prove how strong she is in the cold, and Brock to just break stuff for no particular reason.
Here's where it gets fun. Since Sejuani doesn't really have any elemental powers other then her power over Ice, she may only learn Normal, Fighting, and Ice type moves, no matter which form you get. Additionally, she must solo every Jynx you meet, as she mistakes them for her eternal rival, Ashe. Finally, in order to prove her resolve, you must switch her in whenever someone uses Blizzard or Ice beam.
Have fun! If you want it harder, I can arrange that.