I'm looking to buy any of the following pokemon names.
Gen 3/4 greatly appreciated.

Slaking
Arceus
Giratina
Garchomp
Registeel
Regirock
Regigigas

 

All/Some of the Regis were owned by Ryan who is a scammer. He might have sold them off but just be cautious.

Proof: Selling pokemon names

He sold me some names before so I would not put it past him.

A lot of Pokemon names are also held by the hoarder who owns Mewtwo/Mew. He might own some of these.

Best of luck.

Victoria / Bubbles