Guys, I can really assure you that HAS been caught on a legitimate italian copy of sapphire without any AR hack nor anything. If I can do something to further research on this (more pkm or something), then tell me what to do.
EDIT: If it can help, the cartridge's battery has run dry, and I had used the jirachi from Pokémon Channel in the past to fix the berry bug (not sure if that changes the RNG workings but I thought it would be something to mention).
EDIT2: Actually, might want to check if it perhaps was an egg, rather than been caught in the wild, because that probably was how I did it.