Yeah Cold and Chilled both seem to perpetually be in their true forms, perhaps because they are older than Freeza and have had time to get used to their power more
Pr sure he's referring to when Gohan said initial Mecha Freeza's power is nothing, he gets way stronger
http://comic.dragonballcn.com/list/0.Dragon_Ball-buyao_daolian_ya/0.jp_Kanzenban/DRAGONBALLvol23/014-iNfON.jpg