Omega EzFlash over the EVERDRIVE is my choice

PRODUCT LINKS ARE IN THE DESCRIPTION

EXSEK EZFlash Omega Cartridge Flash cart for Gameboy Advance GBA
https://amzn.to/3qPZOVJ

USB Rechargeable AA Batteries - Lithium Batteries(the ones I use, I didnt want to deal with cords)
https://amzn.to/3oNafYc

Variety of USB Rechargeable AA Batteries - Lithium Batteries(some have more juice if you dont mind dealing with cords to recharge)
https://amzn.to/38duXdp

EVERDRIVE X5 GBA(just incase its the one you have to have)
https://amzn.to/2K22cYK

K101 Plus(out of stock at the time I put the link in here)
https://amzn.to/37URMlW