HASHIRAMA'S ABILITIES

Hashirama is reputed as the most powerful shinobi of his era, his might being so vast that it earned him the title of "God of Shinobi", and having been called the strongest shinobi even by his enemy Madara Uchiha who, on countless occasions admitted his inferiority to the legend. His strength was so greatly respected by the shinobi world that Madara himself claimed Hashirama was the one person whom he most admired and detested, as well as the only person capable of stopping him, something that dated even back to their childhood. Madara mentioned that fighting all five current  was trivial compared to his battle with Hashirama, and that with only one of them present, the landscape would not change as drastically — a reference to the battle between the two that created an entire valley.
Kabuto Yakushi claimed that Hashirama's might was so vast, that there aren't any living shinobi in the current era that could match his level of power. It was such that many considered his prowess to be a mere fairy tale much like the existence of the Sage of the Six Paths.The most common example was his ability to not only fight on equal footing with Madara despite the latter possessing an Eternal Mangekyō Sharingan and having control of the Nine-Tails, but also survive the battle and ultimately achieve victory against his former comrade and adversary.

Stamina and Life Force

As a Senju, Hashirama inherited an extraordinary life force, as well as physical energy so much so that he was able to fight Madara for 24 hours non-stop and still have enough energy to stand on his feet. Likewise, his chakra was also shown to be remarkably strong; a testament to its fortitude was witnessed through Hashirama's use of his chakra alone to deter his brother from attacking, which almost caused the Naka Shrine to collapse.He was also able to resist the control of Orochimaru's Summoning: Impure World Reincarnation with relative ease when reincarnated with almost his full power, which greatly worried the Sannin.His chakra levels also made him suitable to learn senjutsu and enter Sage Mode.

Ninjutsu

Nature Transformation

Hashirama using Wood Release.

Hashirama was arguably most famous for his unique Wood Release techniques, a kekkei genkai formed through simultaneous use of earth and water-natured chakra. By converting chakra into the source of life, he was able to create wood and plants from the ground of or his very being, causing them to grow to great sizes and manipulate them to diverse shapes and battle uses at will and in an instant, he could shape the entire battlefield for his own uses. This ability appeared to be exclusively his, as no other known member of his clan has ever displayed its use thus far. Even those who obtained this power through unorthodox means, such as Yamato, have stated that their use of Wood Release was much weaker in terms of raw power.

Hashirama using the Wood Dragon and the Wood Human Techniques.

He could create massive forests and gigantic flowering trees whose pollen can render a foe unconscious. He could also make wood clones of himself. Madara later stated that he was the only one who could tell the difference between Hashirama and his wood clones with his ocular powers. Hashirama could create a giant wooden dragon capable of restraining the Nine-Tails by using its immense serpentine body to constrict and absorb its chakra. He could also create a wood golem that works in conjunction with the dragon and is strong enough to catch a Tailed Beast Ball with its bare hands.He could also create protective structures that are able to withstand the destructive force of a Tailed Beast Ball, and could even create several giant wood hands that could block the sword of Madara's final Susanoo.
Along with his kekkei genkai, Hashirama also possessed a unique ability to control tailed beasts.Of all his considerable talents, it was this ability in particular that made Hashirama unparalleled in the shinobi world, so much so that he is regarded as one of the few people capable of completely controlling a tailed beast. At one time, he had many of the beasts in his possession.This ability was greatly amplified by his crystal necklace, which Yamato suggested that he required to control even Naruto's partial lapses into tailed forms.

Medical Ninjutsu

According to Madara, Hashirama was also able to use medical ninjutsu. His skill with which was such that he could heal himself without forming seals, and from the medical ninjutsu that his granddaughter Tsunade — who is considered to be the greatest medical-nin in the world as it is — had displayed at that point in time, Madara surmised that his medical techniques were also on an entirely different level than hers are.

Bukijutsu

Hashirama was also extremely skilled in weapons use, especially in kenjutsu and wielded a myriad of swords, one such had a broad, cleaver-like blade. He also could wield giant shuriken. In the anime, he displayed a creative combination of his weapon skills with his Wood Release techniques, having several roots wrapped around his weapons, allowing him to attack from a longer range with different angles. Hashirama possessed several large scrolls that were roughly his height, presumably to store his weapons. His skill in weapons use was such that he could clash against Madara Uchiha, another highly-skilled weapons user at an equal level, forcing both to shift between using weapons and ninjutsu in order to break the stalemate.

Senjutsu

Hashirama in Sage Mode.

Hashirama's chakra reserves were immense; great enough that he could train in the art of senjutsu and also enter Sage Mode. In this mode, he gains markings around and under his eyes as well as one in the middle of his forehead reminiscent of a third eye.
Sage Mode greatly increased the strength and scale of his techniques. A testament to this, was his Sage Art: Wood Release: True Several Thousand Hands technique, which created a gargantuan wooden statue that possesses a thousand hands which easily towered over mountains and even the Nine-Tails Then after creating it, Hashirama would then utilise the statue's thousands of hands to deliver a barrage of punches of such magnitude that they were able to completely destroy Madara Uchiha's final Susanoo, strip it off the Nine-Tails, while at the same time create a massive crater which became the Valley of the End.The statue possesses extreme durability, as it was able to withstand a barrage of unexploded Tailed Beast Balls combined with Madara's final Susanoo blades. It also possesses notable strength, as it was able to easily grab the beast with one of its hands. Hashirama can also perform Sage Art: Gate of the Great God, a technique that can bind a titanic creature such as the Ten-Tails, making it unable to move due to the bulk of its current form.

Other Skills

As the leader of the Senju clan, Hashirama held proficiency in a wide cross-section of shinobi skills, and possessed at least an understanding of those he did not. He was well-versed in genjutsu and could perform powerful illusions such as the Bringer-of-Darkness Technique, which locked the target in perpetual darkness for the duration of the technique. In the anime, he displayed aptitude in the art of fūinjutsu, using the Contract Seal to break Madara's control over Kurama. Hashirama could use Summoning: Quintuple Rashōmon, which brings out five Rashōmon that can protect him from nearly any attack. He is also adept at using barrier ninjutsu, capable of erecting a Kage-calibre barrier powerful enough to trap the Ten-Tails. He was also a sensor type, though not as good as Tobirama.He had high skill in taijutsu since childhood, with Madara noting that they were roughly equal in this area.
He also showed great tactical skill and deceptive abilities, waiting until Madara became so exhausted that he couldn't maintain his Sharingan to create a wood clone for Madara to strike down so he could attack from behind without his opponent even realising it.