A Pangoro crest : it gives him a +1 increase in defense and special defense, and when his hp drops below 50%,he lose this boost,but gains +2 in speed (and vice versa)
The idea here is to give him better survability,i think this can work well with his other options (bulk up,swords dance,drain punch or the ability iron fist)
Because of how awful his speed stat is (58 base) i think +2 is fair,and his defensive stats aren't that great,so he won't be unbeatable.
Moreover,the idea of below 50% gives him a sort of "rage mode" which i think is nice looking at how angry he seems