Looking at the ARM9 memory for desmume the NPCs advance the frame at a rapid rate for Plat starters. I don't know how it's possible to keep track of it on a cart.
My target frame is 114 but it jumps between 113 and 115, pretty much impossible for me to hit 114 (I'm pausing as quick as I can). I'm gonna take a guess and say you probably need to resave/restart for directions of NPCs, or something. I'll edit again if I have any success. Trying to RNG a Turtwig for a test.
Edit: And yeah, Wild Eep is right, they're all monster 1 frames. Trying to hit your target frame is the issue, though. HG/SS was one thing, Plat is a whole new issue. Especially when the frame advances at a fast rate, if you ever want a shot at RNGing a starter you need a high method 1 frame. Even so, like I said, tracking the frame advancements is impossible on a cart.
Edit 2: ...it's like it doesn't want me to hit my target frame. Stupid seed/NPCs -_-