have put up a guide on how to trade pokemon for GPSP.
Of course, we all know that GPSP doesn't have the feature of multiplayer, but the PC GBA emulator (Visual Boy Advance) has, which is called the gbalink and is different from the original VBA.
I tried to mix up the the emulators and finally got it to work.
NOTE: This only works for trading, not MULTIPLAYER Gaming
So here are the steps:
1. Download Visual Boy Advance Link (vbalink) here: http://www.sendspace.com/file/wxkd5r
2. Extract it to a folder.
3. Open the program 2 times. You should have to VBA windows.
3. Play the pokemon game on BOTH windows, and ready it for trading.
( I used FIRERED version. I haven't tried Ruby/Sapphire so i don't know when trading may start, for FIRERED though, you should deliver Oak's parcel in Viridian City first and have 2 Pokemon before trading)
NOTE: You should really play the 2 windows at simultaneously
5. Save your game via pokemon, and via savestate slot. best place to save of course is inside the TRADING CENTER.
6. Close both programs, then reopen them.
For both windows:
4. Go to OPTIONS>EMULATOR>SAVE TYPE and click Flash 128k (Pokemon games require this)
5. Go to OPTIONS>LINK and UNCHECK the box there.
For the FIRST window:
6. Go to OPTIONS>JOYPAD>DEFAULT JOYPAD and select one. After this, configure it. (Joypad 1 is already configured)
For the SECOND window:
7. Do the same process, but select a different default joypad, and configure it.
8. Now, LOAD both games.
9. The first window, remember has the JOYPAD 1 (or whatever you chose), so you control it using JOYPAD 1, and the second window has different controls. THEREFORE, you can control the 2 windows at the same time.
10. Talk to the person on the right side, and choose the TRADE option.
11. There you go. Trade your pokemon!
FINAL IMPORTANT NOTE: You will be asked to save your game before and after the trading. The flash 128k will make this possible, and you will see a .sa# file, where #is the window used (.sa1 for window 1, .sa2 for window 2, etc.).
Now, to play the save file on the PSP:
1. The PSP has the save files stored on the folder together with the ROM, so if you put the pokemon rom in the PSP folder, the save files will be found there. If you have played your game, saved it through itself (NOT SAVESTATE SLOT method), you will notice a .sav file.
2. Now, copy the .sa# file of the save file you want to use. RENAME this into .sav.
3. Play your pokemon ROM, load your game, and it should be the one from the PC!
If you download the normal VBA (WITHOUT THE LINK FEATURE), it will save files as .SAV automatically, so you can copy it directly to your PSP.
GPSP uses a .SVS file. This file is the SAVESTATE file of the game, not the SAVE FILE.
Only the VBALINK program uses the .SA1, .SA2 files for obvious reasons.
The VBALINK will also utilize a .SAV file. Please do not confuse it with the .SA# files.
Do not also confuse yourself with the .SG files. These are the savestates of VBA, and they CANNOT BE READ by GPSP, meaning even if you rename it to .SVS, it won't load.
Please find out if you can play the .SAV file from the PSP on VBALINK (rename to .SA1) because I haven't tried it out yet. But I believe it will also work since it works from PC to PSP. If so, this will help most people with save files on their PSP's.
I hope my guide is clear enough for those interested.