Pokemon GBAlpha Sapphire is a 3DS ROM Hack by Asia81 based on Pokemon Alpha Sapphire in English. It was last updated on March 29, 2016.
Also, be sure to check out Pokemon Cracked Ruby.
Pokemon GBAlpha Sapphire is a Generation 6 hack. The most important change is the music. Half (~ 100) are from the GBA version (for a bit of nostalgia). This game is also a full random world and a hard mode! Wild Encounters are randomized up to 721, learnable moves are randomized, and all trainers’ Pokemon are randomized with moves, hold items, and abilities. This game has some new Pokemon such as Pikachu Libra, Primal Dialga, Ash-Greninja, Shadow Ho-oh, and Lugia.
If you find a ROM that's encrypted, you need to use the Batch CIA 3DS Decryptor, created by Matif.
Not all games are fully compatible with Citra. If you do find a game that's not working, try using the latest PabloMK7 Citra fork, the continuation of Citra since its shutdown.
Citra is an open-source 3DS emulator for Windows, Mac, Linux and Android devices.
It is designed to recreate the functionality of the Nintendo 3DS system on other platforms, enabling users to play 3DS games in higher resolutions and with improved graphics.