But Mewtwo is a genetically created Pokemon, which by all means should probably be sterile (unless Team Rocket's scientists were told that Mewtwo was NOT to be sterile).
The Regis being able to breed is questionable, since there are Pokedex entries that I believe hint at them being artificial in nature (and hence being called the Legendary Golems), and even Mesprit, Azelf, and Uxie might very well be questionable, but there is nothing to suggest that the Legendary Birds, Latias, Cresselia, and Heatran can't breed, and unless we are to assume they are immortal (which I'm not going to discount the possibility of), without a breeding population, extinction would be inevitable.
Hell, the latter even has both genders-they just won't bred in captivity!
First to answer how so many Legendary Pokemon appear all over the place: they're Legendary Pokemon, they can do whatever they want. Okay, okay, if you want I could probably muster up some explanation for the Legendaries in BW2:
Regigigias & Golem Trio: If the legends about Regigigas moving around continents has some credibility, then I don't think that's a job for just one Regigigas. If you'll let me theorize, being its a golem, maybe it was created by ancient people to help them mold the landscape. The Golem Trio are merely keys to control Regigigas (and possibly help it in landscaping as they do represent structural elements: rock, ice, and steel). When there's a case of multiple Golem Trio for one Regigigas, well, I'm sure you have a few spare of keys, right?
Eon Duo/Lati@s: I can imagine these particular pair (or possibly more?) visit/cross through Unova as part of their natural migration route.
Lake Guardians: A bit tougher, but much like its possible ancient people kept extra Golem Trio around I wouldn't say it wouldn't be that farfetched if Arceus placed extra Lake Guardians. Why? Well originally they were made to give people willpower, emotions, and knowledge and that's a huge job for one group of Lake Guardians to do. So it created multiples and placed them around the world for them to do their thing. As for why they stayed once they did? Well that comes up with a whole batch of theories itself. Maybe they're maintaining people and Pokemon having willpower, emotions, and knowledge? Maybe they're observing what we're doing with these gifts? Whatever the reason, I think that explains why they're in Unova despite originating in Sinnoh.
Cresselia: Cresselia was actually summoned via the Lunar Wing. The ghost girl's father got the Lunar Wing to try and wake her up from Darkrai's nightmare but sadly it was too late. So Unova probably isn't Cresselia's homeland, it just traveled there because it got the call from the Lunar Wing.
Heatran: Heatran seem to appear in places that's deep underground or deep inside a mountain, a place where a lot of pressure would be needed to create. I always imagined Heatran represented a planetary core or from the time when the planet was being formed and everything was superheated rock, magma, and supplementary elements such as iron (pushed together by pressure). So Heatran is probably just a native to the Unova region. That or one could say that the Heatran live deeper down, near to the Pokemon planet's core, and that they have easy access to the places they appear and go there because receive a "call" from the Magma Stone.
Over to
JES's discussion about Legendary fertility:
Mewtwo & Golem Trio + Regigigas: Artificially created so probably can't breed. For Mewtwo it seems like multiples do exist (it was actually never stated in the games that Team Rocket created it, so it's possible it was a well kept secret project that multiple labs did and each Mewtwo escaped because man tried to played Arceus and that never turns out good). Actually, there are some instances of ANCIENT Mewtwo so it could very well be possible some Mewtwos are maybe naturally mutated Mews (remember its believed every Pokemon had evolved from a Mew ancestor, so maybe it's possible that in modern times some Mews that didn't evolve into a different species had this evolution gene activate for some reason but since the environment does not need a new species it causes a mutation that instead enhances the Mew's capabilities and turn it into a Mewtwo). As for the Golem Trio and Regigigas, I already told you my theory on them. No need to have them be able to breed since they're essentially immortal. I'd imagine Mew and Mewtwos having long lives but not immortal, or maybe Mews are immortal (incase a new species of Pokemon is needed there's a Mew that can evolve to fit what is needed) but when they mutate into Mewtwo they gain a lifespan (and the Mewtwos who are created naturally have a life span).
Lake Guardians: Immortal as they were created from Arceus with a certain major purpose and job.
Winged Mirages, Eon Duo, Cresselia, & Heatran: Long lived, but I wouldn't say immortal. We've actually seen eggs for the Winged Mirages so we know they can breed (though it doesn't seem they're able to do so in captivity). Eon Duo we know there's a population of them, though we don't know their breeding habits. Heatran have genders and probably breed in places deep inside the planet that no man can go and witness. Finally Cresselia I see sort of having a mystical origin, like maybe they just come into existence from the collective energy generated from dreams (maybe even at the same time as a Darkrai). And before you say that's farfetched I point you to Munna and Musharna, in the Pokemon World apparently dreams are indeed a sort of energy.
Not sure if this fits the topic, but I got a feeling the spirit of Pokemon got shifted a bit(for better, for worse?)...I noticed a lot of the focus on the Pokemon shifted a bit more towards the human sides. This is even reflected in the anime...I remember watching the anime long, long ago not because of the humans but rather how the pokemon interacted (that's why for example most people have shown a lot of sympathy towards Brendan's Treecko in the Special Anime trailer because of its movement and how adorable it was)
Now the story gets spiced up a lot with human activity, and that's turns the game into something more relatable somehow...maybe as an adult, it also makes it more interesting?
A prime example would be Looker, which, due to his common appearance and role in the games made him quite popular among the fans, especially providing some sort of weird connection theory for the first games (SS Anne theory, the police man in the cabinet is Looker, SS Anne sinking, Memory loss in ORAS)
What I am trying to say is, if Z happens, I will expect even more human relationsship to unfold, combined with obvious storytelling. It seems that a lot, including me, enjoy the little dialog from the people around there world...another example would be the awesome girl biker near Mauville City, or Mr. Bonding ...
tl; dr: I am pretty sure concentrating on the human dialogue will give us a lot of theory to talk about, especially in even newer gens or versions
There's only so much you can do with creatures who basic nature are animalistic. Pokemon seem to be "in tuned with nature" thus anything they do is natural and isn't setting anything off balance. So the story needs people to stir things up and add in layers of depth. Humans have needs, wants, desires and they act in ways to accomplish them. This leads to interesting stories.
As for the Pokemon acting more human, indeed that's a shift but I always saw Pokemon are being as intelligent as people but, while humans chose to rely on their intellect, Pokemon chose to stick with their instinctual routes thus act more like animals. However prolonged exposure to humans do have effect on Pokemon's behavior, especially those owned by trainers who may adapt some habits from their master. Of course all this depends on the adaption, Brendan's Treecko in the ORAS trailer does act more like an animal then say Ash's Pikachu, though at the same time I can see some "human" traits to it.
Who knows what they have planned for Z/XY2. If I would be allowed to guess, I'd say I wouldn't be surprised that Lysandre's messing around with the Yveltal/Xerneas caused some disturbance in the natural order and Zygarde now needs to fix it. But in what way would it be presented? A remake like typical third versions before Gen V? A sequel game like BW2? And that's even if that's what the story is going to be about. We'll just have to wait and see on that one. As for what human element can be involved, well, aside from Xerosic the other Flare scientists were never caught (and Malva got off scot-free and she sounds like she stil perfectly believes in Team Flare's plans). Another speculation, maybe instead of Zygarde being used to restore balance what if the remnants of Team Flare maybe will try to use it to create a NEW world order? Who knows, though one final thought on this subject: what happened to Lysandre? Sure, we presumed he got buried under rubble, but did we ever find a body? And being he was directly exposed to the light of the Ultimate Weapon wouldn't that mean he's immortal? Hmm...
I don't think the XY being a decade after RGBY is confirmed, but it is the most likely thing, since a TR grunt in Johto says he's moving back to his region of origin (Unova), and in Black and White, he's living in Icirrus City. He's living there with his wife and son, and then tells us that he left Team Rocket to start up a branch in Unova, but soon after arriving, he met his wife and fell in love. Since his son seems to have a preschooler sprite, that puts his age around 3 or 4, which would seemingly confirm the timeline being ten years long. But yeah RBY/LGFR = RSE/ORAS --- 3 years ---> DPPt = GSC/HGSS ------> BW --- 2 years ---> B2W2 = XY
And let's not forget about Caitlin who had visibly aged between when we saw her as head of the Battle Palace in Gen IV and member of the Unova Elite Four in Gen V:
(Yes, this is not an official piece of artwork, but I think it's fairly accurate of what artwork and sprite we've seen of
her)
I'm not saying the prediction of 4/5 years inbetween in wrong, it sounds about right, I'm just saying we have no confirmation. And let's not even get started with the Pokemon World Tournament's age inaccuracies...
I find it highly unlikely that it is radiation, because aren't usually mutations caused by radiation more harmful than good?
I'm almost tempted to think that maybe we are seeing some sort of living fossils of the ancestors of these modern Pokemon. Perhaps the fragrances or herbs somehow trigger archaic genetic material leftover from these earlier forms when inhaled by the female while breeding, resulting in these "baby Pokemon".
Obviously, these baby forms are no longer as common, because from a survival standpoint, the babies that hatch straight into their second forms were more likely to survive and breed than those that didn't.
Some of these "baby Pokemon" still apparently thrive in some regions for some reason, while they are all but extinct in others.
Siggu also suggests that they might have been genetically engineered over time like we've done with different breeds in real life, somehow using these incenses, though with these baby forms in the wild, we are forced to come to the conclusion that this means these wild baby Pokemon are "mutts" that have survived in the wild. Either that, or they originated in the wild, and humans eventually bothered to find out the different conditions that make them, thus making it possible to breed them in captivity.
I would say these Baby Pokemon needed from incenses are mutations, but of a chemically induced kind instead of radiation. The herbs and the fragrance they released caused some genetic triggers to go off that had caused the offspring to stop maturing within the Egg at some point thus allowing us access to a "per-evovled" stage of that Pokemon species.
As for how they can be found in the wild, that could be triggered from other things. It's stressful in the wild and in some situations it could be better for survival if the Pokemon hatched early so that it could start defending itself rather then waiting to fully mature in the Egg thus be vulnerable for that entire time. As
JES said, trainers from foreign region see these per-evolved forms of Pokemon and wonder how come they can't hatch that Pokemon normally, so people found a way to trigger it artificially with incenses.
