Not my work thanks to eepp for this :)
Super-advanced Pokewalker tricks:
You folks probably saw my flawless Timid HP Ice Pikachu in the Discuss My Pokemon thread last night or today. So in this post I will go over the advanced stuff I did to make it possible.
Abstract: You can advance the frame by 2 for each Pokemon sent over to the DS without turning it off (I left mine in sleep mode while catching). The IRNG call used (which indirectly governs the nature) is equal to 192C + P, where C is the number of Pokewalker-to-DS connections are used, and P is the number of Pokemon caught (including the target). This is assuming there are no connection errors, which proceed to render the nature unpredictable.
Make sure your stroll is configured to produce the monster you actually want to catch. You can figure this out before starting the RNG process, so doing it now saves you aggravation later!
Find a seed with good IVs. A viable seed has zero delay at some year in legal DS time (you can't be picky about the year because only one year works per seed!). With current knowledge, only odd frames can be achieved, and you can't go higher than 1079 (and you'd need a completely empty PC for that!).
Find a point on the IRNG with an acceptable nature. As things stand now, this is a pain in the neck. Run an IRNG search on your target seed from (192*(1+[P/3])) to some large number, where P is the number of Pokemon you have to catch to reach your frame (P=[(F-1)/2]+1). Export this to CSV and open it in your favorite spreadsheet program. Use a find/replace function to search for spaces and replace them with nothing so that the egg PIDs can be manipulated. Make a new column with a formula to convert the hexadecimal PIDs to decimal, like =HEX2DEC(A1) [or wherever your PID is]. You will also want another column to determine the Pokewalker nature from this. The algorithm is Egg PID mod 24, so a sample formula would be =MOD(B1;24). Match the resultant numbers to this list to determine the nature. Because mod 24 returns a number from 0 to 23, Quirky (24) cannot be selected, which is probably a good thing.
The next challenging part is finding an acceptable IRNG frame to use. An IRNG frame I is acceptable if (I-P)/192 is an integer greater than P/3. The resultant integer is the number of Pokewalker-to-DS connections you have to make in your journey. It has to be at least P/3 because that is the minimum number of connections you have to make to get your target frame!
I would like to take the time to mention that I do not know how the ability is chosen at the moment. All my Pokewalker RNGing has been in the Yellow Forest with single-ability Pikachu.
Make sure you can reach your seed before starting, in other words calibrate or make sure that you have already done so. Set the DS clock to a time near the seed (you have to use a year such that the seed's delay is zero) and attempt to start the game at the correct second. Send a few fodder Pokemon to the DS and compare to the Wondercard IVs list for the target seed and seeds with the same delay (0) but several seconds off in either direction.
Once you can achieve your seed, try to land it and begin your quest. Catch all the Pokemon you need, and send them over (via Receive Gift only) in the requisite number of connections for nature purposes. In between connections, I recommend leaving your DS at the Pokewalker connect menu in sleep mode and plugged in. Also, beware of connection errors! Even one error will cause you to lose control of the nature!
The clock striking midnight appears to have no effect on the RNG's advancement, and neither do items your Pokemon finds on the ground.
I hope that helps all you budding Powewalker enthusiasts out there!
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-Wild Eep
Information regarding manipulating the RNG to obtain a desired ID/SID combo when starting a new game and Honey Tree research can be found here.
