Which enemies would he beat and which would give him a hard time so he loses?
Without his swords, if the past enemies are the same level as when they lost to Luffy then in paradise :
Crocodile, Enel, Lucci, Moriah and Pacifista would all be annoying to put down but they are still too weak to trouble Zoro
New World :
Hordy also can’t do much,
CC also can’t do much since Zoro can create tornados that cancel out CC’s air canceling ability,
Doffy is the problem, while he is slower and weaker than Zoro he is a pretty intelligent guy so he would try and keep this distance and win that way, but I don’t think he has enough AP to put down Zoro,
Cracker will actually win this pretty easily, his attack power was fairly decent and Zoro has no way of defending himself from multiple sword attacks,
Katakuri if he uses his brain will also have an easy time but if he stops using his weapon and tries to win with mochi kicks and punches it will take him hours before he can win