I feed a wide variety of treats including the more common brands (pupperoni, beggin strips etc..) to decent brands (innova, nutro etc..) as well as people food. Of course it is all given in moderation.

I find for intense training cooked liver or chicken works well.

With a puppy that young though you don't want to vary the diet too much too fast (as you may have experienced with the diarrhea the other night). Just a few easy to digest treats, carrots, chicken, his regular kibble etc...