I actually have someone else who also mentioned having a Manaphy; apparently it's still in the Egg as she has two copies of the Ranger games and says she'll never use the other one. It sounds like an untouched one will be coming my way soon provided she comes on to complete the trades. All to get started on a Dragon run of White. :)
Thus, keep an eye on my page for the next 40 or so hours; if the trade completes, I won't need Manaphy and I really won't care what the second is. Shaymin, however, I will still need, so the Poké Transfer will not be wasted. In fact, still go ahead and transfer Manaphy just in case the trade doesn't complete; I'll look at the stats and info before trading for it.
Since Shaymin is a Sinnoh catch, I'll be trying to hack its Event through my Action Replay one day (that path is considered a great Egg-hatching road). If it works, I can get a second; heck, I might even get my own Arceus (non-Event), though technically it's illegit. Wonder if I can encounter Darkrai. Mind, the Enigma Stone in SoulSilver is of the most interest to get a non-roaming, stationery Latias.