I have some sympathy - I decided I wanted a Spore Shroomish for my SoulSilver (which, assuming the breeding still works likes it used to, requires me to have both parents with Spore); and annoyingly, I haven't got a single one in Gen IV anywhere (and only one level 24 Breloom). So a great deal of time on and off rapid levelling in Diamond to get two caught from the marsh to level 45 (from about 23) is going to be required...