We do have sprites, it's just we can't reveal them due to previous thievery. But you're more than welcome to try and join the staff and make them better.
Being a staff member there, former Mod etc, I know that Fangking only likes to have Kangaskid as a spriter of Pokemon, seeing as he doesn't want to have clashing styles. Trainer sprites are done also, but there's still plenty more to be involved with. Come along and show us your skills, you never know. :)