Josh Reyer

I don't remember the Japanese original, but given the translation, I'd be dollars to donuts the original was kata-geiko, or ichi-tai-ichi kata-geiko, and "one-on-one combat forms" is simplification-cum-explanation by the translator. If you consider how Takeda demonstrated -- letting volunteer uke attack him how they liked and then throwing/pinning them, this would have been quite distinct from the kata-based training of other jujutsu ryu-ha, or the rule-based competition of kendo.