It is safe to say that most characters in Demon Slayer have gone through some form of transformation by the end of the series. Owing to the developments during the latter parts of the manga series, fans have started questioning the strength of both Nezuko and Tanjiro Kamado.
These characters drastically improve their physical and combat abilities by the show's end. The comparison will be based on physical ability, skill, and overall combat abilities and their effect on the individuals.
Disclaimer: The article contains major spoilers from the manga.
Tanjiro vs Nezuko in Demon Slayer
Physical ability
Nezuko would be far stronger than Tanjiro in the base form in terms of pure physical abilities. But Tanjiro gained superhuman strength and speed owing to the activation of the Demon Slayer Mark.
Comparing the two in these forms, Nezuko might still outperform in terms of speed and strength. However, the regeneration rate is a huge difference since Nezuko can almost instantly regenerate a limb after it is severed.
Overall combat ability
Nezuko is ridiculously strong since she could single-handedly drive Daki into a corner. Her transformation grants her enhanced speed and strength and a much faster regeneration rate. That being said, Tanjiro will undoubtedly outclass Nezuko in terms of his overall ability to fight.
He is one of the few characters in Demon Slayer who can use the Breath of the Sun. Additionally, he is well-versed with Water Breathing techniques which allows him to perform defensive maneuvers as demonstrated in the Entertainment District arc. This, paired with the activation of Demon Slayer Mark, will surely make him a far superior combatant compared to Nezuko.
Tanjiro can be considered on the same level as Hashira, given that he and Giyu Tomioka were able to defeat Upper Moon 3, Akaza. Nezuko can be ranked at the level of an Upper Moon 5 since she is considerably weaker than the likes of Kokushibo and Doma.
Verdict
Both siblings are quite strong, but certain factors would affect the outcome of this battle.
While Nezuko is strong in her transformed demon form, Tanjiro would be the winner of this battle for a few reasons. He can activate the Demon Slayer Mark, is a user of the Breath of the Sun and has perfected most techniques from Water Breathing.
The versatility in swordsmanship and the enhanced physical strength due to the mark will make him the winner of this battle.