I've recently bought a KrzysioCart (it hasnt arrived, it's quite difficult to send things to Colombia), before it arrives, does anyone know if it can support the SMB PELLSON'S practice rom?

Yes, Pellsson's practice hack uses mapper 1 (MMC1), which is supported by KrzysioCart.

Can confirm, I used to use a KrzysioCart until I purchased an EverDrive, Pellsson 5.6 works as expected on it.

Thanks for your help :)