I'd have to agree with above; due to reasons that had been stated, when it comes to Dowsing Machine, it would have to be from generation five.
However, aside from that, I'm actually quite fond of Itemfinder from generation three of games. It's not exactly Dowsing Machine, per se, but it is a variant, as it helps us find and get a hold of hidden items. It chimes bells every time you take a step or two, if I remember correctly, and the close you are to an item, the louder the sound would alarm; it was actually quite easy to utilize.
If they had kept this key item in future games rather than replacing, I believe it would have been better overall, in many ways. Of course, some might not have found it to be very helpful, which is understandable, but I'm sure many of us have. Plus, with some simple edits to its function here and there, Itemfinder could have gotten even better.