update: I found a way to get an xp multiplier and it works for all pokemon 3ds games (X, Y, omega ruby, alpha sapphire, sun, moon, ultra sun, ultra moon)
1. Follow the tutorial linked at the bottom of this page until 2:45
2. Click personal stats on pk3ds and click enhancements
3. Tick modify exp yield in the bottom left and change the "final xp value (%)" to whatever you like
4. Click modify all in the right side of the bottom box
5. Accept if something pops up
6. Close the personal stats editor window
7. IF YOU'RE USING CITRA THIS IS THE LAST STEP
Skip to 3:55 in the same tutorial and follow it to the end.
IF YOU'RE USING A PHYSICAL 3DS FOLLOW THIS STEP AND CARRY ON WITH ALL OTHER STEPS
Skip to 3:55 in the same tutorial and follow it to 5:17
put the edited rom into your roms folder on your SD card
put your sd card back into your 3ds
power the 3ds on and hold start straight away to open godmode9
go to your roms folder through godmode9
go to the rom you just put in the roms folder and press A
on the bottom screen, press A on "NCSD image options..."
press A on "build .cia from file"
when this is done, press start to exit godmode9
go to FBI on your 3ds homescreen
click SD, click gm9, click out
click A on your game and "install and delete CIA"
press start to exit to the home menu
your game will appear on the home menu after a few seconds
the tutorial:
