Glad to know you know your way around VBA, that saves a lot of hassle. Main thing to note here is if you mainly use savestates then save properly somewhere and use file -> export -> battery save. Even if you do not and use conventional save methods you probably want to be using that to export your saves anyway rather than finding the finding the "normal" save.
Linker is the main term but some use cradle as well. I doubt you will find anybody willing to part with one though (maybe if their cart breaks but even then they are really nice to have) and even by themselves they can fetch a reasonable price (other people have linkers break or something and as mentioned they are just plain desirable items).
If you just wanted saves then you can use a cable (they are really quite simple to make* and your parallel port is well protected) or one of the programs (if you want programs then you need an EZ4) on
http://chishm.drunkencoders.com/SendSave/index.html as that is your best bet. The stuff on
http://www.ziegler.desaign.de/GBA/gba.htm is probably overkill for what you want.
You could also use a DS or DS lite with a DS slot flash cart and transfer the saves from that using
http://filetrip.net/f3228-GBA-Backup-Tool-0-21.html (sorry I should have mentioned that last night)
*
http://pokemonhackingclub.webs.com/apps/fo...-an-xboo-cable- is the result of a quick search although there are better guides already linked on those sites from the first post.
All I will say on the matter of gamesharks/action replay type devices is they can only really be used for temporary storage and trying to get things off your PC is not possible.
"so i can trade with my Gamecube"- this might make flash carts a bit tricky (the gamecube is fairly set in it's ways and flash carts tend not to play nice- nobody I know of has bothered to hack the gamecube side of things either) so yeah if you can inject saves into games that would be better. One sidenote- if you plan on using I think it was PAL park with DS pokemon games you can use a flash cart if you patch the DS rom with pokepatch
http://nds.cmamod.com/nds_downloads/
Flash carts- Flash carts are carts that sit in the actual hardware and trick it into thinking it is an official cart often along with a few nice extras. On more modern consoles we tend to abuse optical drives, USB support, hard drives if they have them and SD cards but on older hardware custom made cards are the method of choice. Originally there were many for the GBA but nowadays you are limited more or less to the EZ4 if you want a full fledged GBA capable cart but that is OK because the EZ4 is excellent. There have been a fair few threads on the subject the last couple of weeks in this section and others in the GBA subheading if you fancy reading up (the main thing to take away is you will need a miniSD and not a microSD to mini adapter). On the DS you have a few more options though.