As I abused in the Tipping the Scales tournament, Rhyperior may be OU now, but Rhydon is still solidly NFE. And if you look, it has almost the same stats and the same typing. So just use Rhydon in UU. However, I should point out that it plays a lot differently without the more or less permanent SpD boost from the omnipresent Sandstorm.
Edit: By the way, I use Donphan a lot, and love it. It handles DD Mence, Metagross, Flygon and Scizor (in a pinch) as well as you could want, has priority, and can set up Stealth Rock without the need for a suicide lead (which I hate). It's not the best Rapid Spinner, since it can't use Toxic Spikes and isn't immune to Toxic Spikes, but it definitely has its uses. Electivire, on the other hand, is a mystery to me as well.