I pronounce it 'Reg-ice', as that makes more sense to me than 'Regi-ice'.I sometimes call Tropius 'Troph-ius' by accident even though there isn't a 'h' in it. But I get annoyed when people call Ho-Oh 'Hoo-ooh', and when people call Regice 'Regi-ice'.
How do you pronounce Regice? I thought its English name was the same as the Japense one.