So,of what i know u have to insert the MfoMT or FoMt GBA dame into the second slot while Harvest Moon ds Cute is in the 1st slot.then he comes to the valley on Saturdays!Ushi no tane says most of it.they said this:
Cliff will only appear in your game if you plug in your copy of FoMT or MFoMT. He will keep to himself all day on Saturday when he visits and spends the morning inside the Inn. In the afternoon he will walk by himself to the Waterfall area where he will silently gaze at the water, as though he was quietly thinking of something.