no... u can only get Regice in Ruby, Sapphire, and Emerald. Not Diamond, Pearl, or Platinum.
Clefa's can be caught in Mt. Coronet near the Celestic Town exit. They can only be caught at night time, I believe.
Use strength
It's called MT. Coronet, and Nosepass and Magenton evolve in MT. Coronet when leveled up
In mount cornet, at least that's where i found mine without the national dex
You can find it: -Mt. Coronet -Trophy garden
run around in mt coronet you will eventually find it
In Mt Coronet and Trophy Garden (daily pokemon)
You can find CLEFFAs in some parts of Mount Coronet, and if you have completed the Sinnoh Dex you can find some in the Trophy Garden by speaking to Mr. Backlot.Good luck and I hope you found this helpful!
you need to get to the spear pillar that is the top of the mount coronet to find him
in mount coronet
Cleffa can be found in Mt. Coronet in the morning at the North and South Entrances.http://bulbapedia.bulbagarden.net/wiki/Mt._CoronetAlso, Cleffa can be found in the trophy garden if Mr. Backlot says so.http://bulbapedia.bulbagarden.net/wiki/Trophy_Garden
you find dialga in mount coronet
cleffa evolves at level 30 you can find it at mt. coronet
on top of mount coronet
it is found in mount coronet
Its at the top of mount coronet