Also, of note, cloned Pokémon are still legitimate in all ways, it's just a second (or third, or fourth) copy of it. I know I'll want to clone my Keldeo to have one in both Black and the B2/W2 games one day.
Ah, noted. I don't have one myself (the right one isn't even available in stores here), but I know most things in Action Replay I likewise disapprove of, such as creating a random encounter with a wild Lv.5 Arceus on Route 1 (come on, really?). If I ever do something like that, it would only be to unlock event items; there is great discussion on whether this constitutes cheating in the case of items never released. In that case, Arceus - while catchable at the Spear Pillar - cannot be legitimately obtained because the event item was never released. This is why some people turn to things like that, especially if they never get to see an Event one.
Unfortunately I don't. I have only recently acquired some of the older games and will one day be using Action Replay to unlock the event items, but Pearl/Platinum I haven't gotten started on yet.
Cloning can only be done with Action Replay, or using certain Web sites, but there are people in the Quick Trade forum who are verified cloners in a special cloning request thread. You can ask for one of them to clone it; it's a good way to get someone a Pokémon that they normally could never get (either due to not being released in the area - like Australia still needing a Keldeo - or by not being able to get the event while it existed). Some people literally collect nothing but these events, having dozens, even hundreds of them from different countries, and will trade other special events ones for them (often clones or duplicates if they have multiple from multiple eligible games). Me? I'm happy just having one of each Pokémon, I don't care where it comes from. LMAO
I don't have an Arceus unfortunately, but what's the chance a clone of the Jirachi might be available? I have Colosseum but I have no bonus disc, and Jirachi is among the rarest of rare; I'm wondering whether it will arrive via a future B2/W2 event since it's among the few legendaries NOT to show up there.