What does Donald Trump have to prove to win his WSJ lawsuit over ‘fake’ Epstein card?
That what was said in the WSJ's article was untrue, and that its authors and the WSJ, the Dow Jones News Corp, and the journalists who wrote it knew the information in question was untrue.
Actual malice is VERY hard to prove when the defendant is a public figure. Public figures are considered to be less vulnerable than people living private lives.