Pokemon Games on the 3DS

Since GBA remakes, always is not possible to obtain all Kanto pokemon in a pair of games, always needing to transfer.
If you want something near, maybe you can try X and Y games. This is the list of unobtainables:

http://www.serebii.net/xy/unobtainable.shtml

Well the closest would either be x and y or sun and moon with having the most gen1 pokemon being able to catch in those games. Either One of those should be fine for you.

Trading would be required for whichever game you pick, if only to evolve the Pokemon that have it as a requirement (e.g. Gengar). There's online trading these days, or you may be lucky to have a friend with a compatible game.

In XY I was lucky enough to get another gen's starter through wonder trade, then bred it and traded for lots of other starters and similar stuff. Also there's a catchable Mewtwo.
Edit: you're given gen1 starters as well

I think you can catch the most in ORAS (overall, not just from Kanto, plus there are like 20 legendaries in there), but beware you can only get 1 starter per generation (Ex. If you get torchic, you can't get mudkip and it's evolutions unless you trade for them, the same goes for starters of other regions like charmander, bulbasaur and squirtleyou will have to trade for the rest. Also there are pokemon that have some special evolution requirements, like alakazam that require you to trade them in order to evolve them.

Edit: supposedly you can catch all (Up to gen 6) between ORAS and XY.