can i play .gba files on Acekard2i with AKAIO 1.5?

i heard that the AKAIO 1.5 supports GBA roms is this true?

no

They may have meant that it has a built in GBA loader, which works with the Slot 2 expansion card. So you don't have to use Homebrew to load GBA games, and can just use the Firmware to do it. Either way, you still need the Slot 2 Expansion card.

The original firmware also supports with TirithRR said, but AKAIO has BETTER compatibility.

you can if you have a ram Expansion card like this.
http://www.dealextreme.com/details.dx/sku.2967

ez flash 3in1 expansion pack
Try it

but you still need a gba loader