While this has been brought up since records began and its opinion based, im confused about the opponents minato supposedly took by himself.
Example, he never took on the kumo duo.
It has always been a speed duel between Ei and minato with Bee interfering at the last minute.
However an interference that bee himself later didn't recognize as his fight when he claimed an inexperienced ms sasuke to be the strongest shinobi he has faced. But also claimed until sasuke' avoiding his number 8, nobody apart from Ei has done. Stating that, if he had fought minato, his number 8 should have landed going by that statement.
Next it baffles me when its claimed he took on Kurama and Obito at the same time when i remember obito summoning kurama to konoha and doing battle with minato alone. After the fight, did he and kushina (something that people always push to the back of their minds), overcame kurama.
Minato didn't face what hashirama faced which was madara+ kurama. He faced them individually with help from kushina in respect to kurama
He later received help with the distribution of his kunai's by konoha fodders.
Anyway kishi gives every shinobi a last showing to state their claim before they die, with the exception of shinobi's with illnesses or old age which has hindered their strength.
I believe minato that night was at his wits end that night against obito and while he may have other techniques under his belt, i do not think they would be significant enough to drastically increase his strength and that might be why he has now received bijuu powers
well , what you have put is a good speculation. i too agree with this.i personally think that we havent seen much about Minato.whatever we have seen is a part of his exploits(his clash with A and B).we cannot come to any conclusions based on a single clash, since A said that he was not able to surpass Minato, it means that Minato would have had many techniques under his sleeve not to mention his speed feats.
regarding the kumo brothers,i think they were dead by the time Minato became a jounin,so there is no way that he would have met them.
the kunai throwing by konoha fodders is not a big thing i guess. infact,during their first meeting,it was Minato himself who threw the kunai ,so ithink that the konoha fodders are not ncessary for spreading the kunais.
regarding Bee using his 8tail on Minato,i think that Minato would have escaped it,since both A and B were terrified by Minato(not literally terrified,but they accepted Minatos superiority overall).
the bijuu powers of Minato were not used because of lack of techniques or something,it might be used to finish the war quickly( and since the juubi is their opponent,it seems that Minato is trying to speed up the process). its not abt drastically increasing his strength,its about the techniques which work at a given time.(for ex: Minato has to use FTG to get behind Obito as there was no other technique that could be used at that time).
regarding his battle with kurama and obito,obito was trying to distract him and Minato,in order to destroy Obito had to fight him while the 3rd was taking care of Kurama. its not that he cannot take care of kurama,but Obito was the cause of all htese and so the first thing he has to do was to defeat obito so the kurama can be taken care of elatively easy.