Ok how can I explain this. Just because a ninja has a justu doesn't mean he should use, u people on this base should really stop stating that if hashi had used said justu its gg or that hizuren doesn't have anything to counter such and such, justu aren't the basis of a shinobi strength its skill and proficiency. Hizuren is able to use a B rank justu with the power of a S rank. Oro was obsessed with all forbidden justu and had vast knowledge on hashirama. There for he used him as best as the edo tensei would allow, the reason he didn't use flower tree world is obviously because it be stupid to use such a justu in such an small and confined area. It's been stated that he surpassed his predecessors and was considered the strongest kage just because hashi has beeqn shown with a strong arsenal of justu and abilities doesn't mean that the latter is false. People forget to realize hashi's power and strength has been shown or stated when he was in his prime. We've only seen hizuren in his old age and yet he was able to hold his own against to kages and oro at the same time with no help, while battling his own inner turmoils.
