Hiruzen was called "The God of all Shinobi" and The Professor (プロフェッサー, Purofessā) due to his vast knowledge of jutsu, purportedly knowing all the jutsu within Konoha. Hiruzen may well be "The Most Intelligent Shinobi in Ninja History". The first jutsu he is seen using is the Telescope Technique which allows him to observe others through his crystal ball over long distances. With Roof Tile Shuriken, he can launch nearby tiles at an opponent with varying intensities, and by throwing a single shuriken at an opponent he can replicate it to surround the opponent through Shuriken Shadow Clone Technique. This shows that Hiruzen is adapted to every battleground in Konoha and is able to use his surroundings to his advantage.
The more battle-oriented jutsu he is seen using primarily consist of elemental attacks, specifically attacks dealing with fire and earth. Fire Release: Fire Dragon Flame Missile allows him to exhale a stream of fire from his mouth. Earth Release: Earth Flow River creates a river of mud beneath the opponent to throw them off balance, and he can use the mud with Earth Release: Earth Dragon Bullet, which creates a dragon's head that launches mud balls at an opponent. These projectiles are ignited with Fire Release: Fire Dragon Missile. Earth Release: Earth Style Wall allows Hiruzen to spit a stream of mud that solidifies into a protective shield.
Hiruzen also has a personal summon: Enma, the Monkey King. Enma can turn into a diamond-hard staff which can alter its length and width at will. This staff is Hiruzen's weapon of choice, and he shows great proficiency in wielding it.
Hiruzen is unarguably one of most powerful shinobi in Shinobi History. Iruka even stated that Hiruzen is said to be the most powerful Hokage. Enma commented on his battle with Orochimaru that it was "miserable" compared to Hiruzen's prime even though Hiruzen had clearly been able to withstand Orochimaru, Hashirama and Tobirama, even to the extent of repelling and withstanding Hashirama's Wood Release and Tobirama's Water Release techniques and able to blow up both Hashirama and Tobirama's arms and legs respectively. Hiruzen was also elected to be Hokage at a very very young age by the previous still living two Hokage's. This showcases the trust that Hashirama and Tobirama had upon the Hiruzen's abilities to protect Konohagakure.