Let's call it "Item Distribution Proto X".
And games it can link to are Game A, and Game B.
If Game B has some sort of inventory system where that item does appear,
the item likely (not 100% sure of course) has its data probably in Game B (though it could be not intact in case devs decided against including it). So you could do a cheat code search (using your favorite GBA emulator which isn't no$gba) and unlock that item anyways in Game B.
Assuming text isn't compressed, you could use a relative search tool (mokeymoore) to find what each byte value matches as a letter, then create a tbl file you use with a hex editor while opening any of the roms involved, and you'll find and probably can edit the text in question.
(By the way, in the off chance one of the games involved is a localization of Megaman Battle Network 5/6, don't bother - because the localized versions deleted tons of link-related features, even the data which would be transferred, to save cartridge space. So a good idea would be to use the Japanese versions.)
I am not sure what conditions you might have that would allow you to ask this but not speak further -- for the most part as long as you do not release the ROM it is more or less all good, though I suppose if it will get someone in trouble then eh. The list of wireless compatible games is very small so I could probably guess/infer some things -- you say one game but not another, this means bit generations is probably out and as it is an item transfer that means pokemon, megaman, boktai or possibly mario golf and mario tennis. You say one game and not the other, however it is for good reason that the same game but slightly different things like megaman and pokemon are considered cash ins so I am guessing two actually different games which means likely megaman 5 and 6 or boktai, or the mario sports games.
2003-2005 had tons of games scrapped: a near finished localization for Boktai 3, Legend of Stafy, and lots of first party Nintendo games (like Ao no Tengai, with a console couterpart TM:Namida having also a cancelled localization).