there is almost no pid-iv association at all any more. any iv spread can go with any PID. this isn't true for mystery gifts, but everything else does it that way. the only thing he would have to worry about is the different PID generation methods and those are mostly just XORs of the upper32 bits of the next seed advancement.(also different for mystery gift but still rather simple) we're also still finalizing egg PIDs and wild PIDs.
egg pids are just upper32 - 0x01, but it seems to be random where it grabs the u32 from. the lowest we've seen is 10 past the current seed and the highest is 32 seeds past.
wild pids are also still a bit of a problem. the formula is supposed to be 1 rng advancement then grab the current upper 32 bits. if the highest and lowest bit of that upper32 bits is equal, XOR by 0x00010000. if they are not equal, then XOR by 0x80010000. however, while that formula seems to work for most, some people(myself included) are finding that the formula is the exact opposite for them. for us, equal upper and lower means an XOR by 80010000. so we're still figuring some things out. once we're done, i'll gladly pass along a list.