RockinX
My goal in life is to make everyone cringe with my puns
I've been using chatots to advance the frame. I determined that in my particular case, the game advances around 86 frames when I face the Pokémon (BW2).For the natures, I use the custom tab in EonTimer. I just input the delay in milliseconds dictated by RNGReporter's Main Window (Method: Gen 5 PIDRNG, Encounter Type: Entralink). it takes a little bit of trial and error, but you can usually narrow down the times for hitting your desired nature frame.
I've done what you said in BW1, though. The first time I thought it'd be harder to do, but it turns out it's not that bad.