So if I deposit, say, an Absol wanting a Raichu, if there's already a Raichu that wants an Absol, would the GTS see that and trade them? Or would it just deposit the Absol?
Every GTS is slightly different, but none of them match up trainers depositing and looking for each others Pokemon. Probably because the traders wouldn't have a say in the nature, ball type, shiny factor, etc.