I would say Diana using her wits against Giganta is preventing as much collateral damage as possible while subduing her. Giganta is about as tall as some of the tallest skyscrapers found in cities, but she isn't the heaviest thing Diana has moved. What's stopping Diana blitzing Giganta and lassoing her before she can react and tossing her like a hammer throw into the ocean?
Cale isn't going to fight Diana in a warsuit like Lex. She'd mainly attack Diana from a social and political angle, working behind the scenes and founding other villains to do the physical stuff for her. And were it up to me Dr. Cyber would be Diana's personal Ultron, who has a working relationship with Cale.