Fly fishing for pike is not something I will claim to know much about, I've done it a few times, don't know much. That said a friend of mine, Herman Broers, Is a superb pike fly tier. He usually ties flies that appear large, but are not bulky. (By large I mean HUGE). Here are a couple of his.

He uses hair like buck tail and Arctic fox as well as synthetics in dubbing loops to form huge "hackles".