Do you have friends? Neither do I, and this hack knows it. All trade evolutions (Haunter -> Gengar, Kadabra -> Alakazam, etc.) have been changed to level-up or item-based evolutions. You can complete the Pokedex entirely solo.
All 721 Pokémon from Generations 1 through 6 are catchable without trading. You can find wild starters, pseudo-legendaries, and version exclusives scattered throughout the early routes. This encourages team diversity rarely seen in standard Y.
If you do not have a 3DS, you can play on a computer using an emulator.