I'm playing platinum and I have been having trouble for days finding a shiny noctowl, ive set the code for noctowl only in Pokemon modifier codes so that only noctowl appears, ive continued my chain and have encountered more than 100 of them n still no shiny patch although the probability is 1/200
It shouldn't matter, but what your cheat code is doing is replacing a Pokemon with noctowl yet treating this "noctowl" as a different Pokemon. So you're simply just chaining different Pokemon yet only noctowl are appearing.
Hope I helped :D?