Bottom line is that gen 1-3 is completely 2d and so this isn't possible at all short of a complete remake a la ORAS or LGPE.
As for the DS games...
I have this really hazy and distant memory of trying one of those action replay codes on White. In that game occasionally there are some differing camera angles, especially one that looks forward from ground level. But they're scripted only for certain areas and such. But there was a video of a cheat code somewhere (that I can no longer find) where it used the ground level camera everywhere. The thing about DS games is that the PEOPLE are still 2D sprites but everything else is a 3D environment, so the sprite will always be facing the camera since that's how 2D+3D integration works, and with this camera angle everyone seems pretty flat. You couldn't really see around you or behind you, just ahead of you, so it kinda sucked. Also, it was hard to tell whether you're on the same z axis as an NPC you're trying to talk to.
There's a couple of areas in the gen V games where they mess with the camera so you can look for yourself and kinda get an idea of what the entire game would have been like like that. And I think the distortion world in platinum played around with it as well. But I don't think it would have been very playable for the whole game since those camera modifiers were used in areas built with that camera in mind.
As for a first person perspective... erm, no. That doesn't really work in an RPG like this. Maybe if Pokémon went VR or something, but it would probably feel off.
