German-Chinese alliance: possible.
German-US alliance: highly unlikely if not ASB. There weren't many pro-Germans AFAIK in America. I might be wrong as early twentieth century American politics are not my area of expertise. American trade with the Triple Entente countries had always been bigger than trade with the Central Powers even before WW1 however. Germany was the second largest industrial power so there must be a reason for that. Wilson was a big Anglophile Don't know about Teddy Roosevelt and McKinley. Does anybody know anything about Germanophiles in American politics.
A German-US-Chinese alliance would be unbeatable and totally cool but the French and British would have to do something very stupid to make that happen.