Let me explain. If I switch in a steadfast Scyther to a Fake Out, will it activate?
Steadfast only happens if you try to make a move, which you don't do if you switch in. So it doesn't activate and you don't get the boost.
Replay evidence
Sorry for getting it confused with Inner focus earlier. I always get the two muddled up.
The move will hit after you switch in. You have moved first, so the flinch won't happen, and Scizor won't get the boost. Sorry.