If that's what this thread is about, it's called Traditional Chinese, not Complex. It's the form of written Chinese used in Hong Kong, Macau and Taiwan and amongst overseas Chinese communities from those countries. Singapore uses Simplified and I think Malaysia does as well. Mainland China uses Simplified and it's used in the United Nations.
Spoken Chinese uses the type of written Chinese used in whichever country you are. Since the characters represent concepts and aren't phonetic, they are the same whether you are speaking Mandarin or Cantonese or whatever. Otherwise the dialects aren't mutually comprehensible.
Traditional Chinese and Simplified Chinese are different translation rights.