Question: what is the strongest zanpakuto?
Answer: 5 ZANGETSU Ichigo mainly uses this for his famous Getsuga Tensho attack. Tensa Zangetsu, his Bankai takes this to another level. He becomes faster, stronger and more durable. A Getsuga Tensho with Tensa Zangetsu was almost enough to kill Yhwach, the strongest character in Bleach.