needs some details on pekin ducklings mainly how they go to the bathroom and if they can be trained to like go in a litter box

No ducks can't be trained to potty in a box of any kind when they have to go they go no matter where they are.But have you considered a duckie diaper, If get a duck also consider maybe 2 since ducks are very social birds and really need to be in pairs.Watch your bird(s) and when you belive they are done with the bussiness then bring them in for a vist with you or keep out side till want to handle them and place into a larger cage and handle them there this keeps all waste out side not to mention all the dirts and feathers they loose alone the way.