Hmm, see I only abuse in HG/SS currently. I didn't know there were that many NPC problems in Platinum. I know this much: you always enter the game on frame of 1. Now, what I would do is this:
Pick a frame that's considreably higher than what you calibrated, so no matter what, you can use Elm calls to verify where you are at. Get it? Like this:
NPC's move it to 5. Target frame=17 or whatnot. Even if you come in on frame 6 or 4, using Elm calls will let you know where you are, advance to 16, exit out, take the eg.