The “Ghost of the Uchiha” Madara is one of the strongest villains Naruto has faced. This question depends on which versions of the characters we are talking about.
If we are talking about Adult Naruto from the Boruto era then he is defeating every version of Madara by himself.
But if we are talking about Naruto at the end of Shippudden then it is a tough task for him alone, that’s where he will need the help of Minato.
Even with Minato’s help against 10 Tail Madara and Sage of 6 Paths Mode, Naruto will have an extremely tough time.
This battle can go either way but Madara might be able to pull off an extremely high difficult win in the end.
Madara, because of his power has more probability to win since his feats and abilities are almost invincible and on a whole another level than fellow shinobis.
These might include limbo manipulation, Rinnegan, gunbai with the ability to convert incoming chakra into wind nature transformation and use in attacks, and Speed which is Massively Hypersonic to Relativistic, extremely rare durability, and peak planetary devastations.
In contrast, with Naruto, Minato’s Flashy speed (Flying Thunder god Jutsu) and teleportation, high IQ, and strategizing ability might stand a fair chance, but not to the extent where Madara goes all out.
Minato’s bound to play defensive and hold Madara back for a while, and Naruto’s abilities combined might have considerable effect, but the ultimate win probably seems to be Madara’s either way.
So Madara wins unless Naruto and Minato don’t have a trump card up their sleeves that matches Madara’s might and exceptional fight.