The reply is roshi.

Let roshi stack a lot in first fight, depending on how low are your stats you may be in need of several rounds of hit endured to reach the defense/ninjutsu needed to win. Just beware that you need roshi to not be the highest hp ninja if not dies under hiruzen in 3rd fight. Just add 2 other ninja that fills in.

If you do not own roshi you can try choza or choji with some healers or the duo hebihime/kimimaro or tayuya/kimimaro with kabuto.

Does not matter if main dies as long as roshi is stacked enough to nuke in one hit sage naruto, 3 rounds after he will nuke minato too, you just need to wait for standard attack to proc evasion.

Roshi is able to solo it if he is alive after hiruzen.

When i say that you may need several rounds of hits endured in first fight i literally mean that you have to reach masked man/kakashi second fight with a roshi able to land on them 20-25k with an eventual mystery so that when you reach sage naruto/minato stage your roshi hits for 40-45k and just suffers 1-2k at most from minato hits.