Well, if we look at Tsukune's "berserk form" capabilities, I think that Tsukune shouldn't have a drawback in terms of speed, when fighting with Akua.
After all, what his berserk form has shown us, is the capabilities of Tsukune's "current" body, which he should be capable of, even in his "normal state", provided that Tsukune has been sufficiently trained in "understanding" his bodies physical capabilities.
While, I'm not saying that Tsukune would b e capable of moving as fast as Akua does, but at the current point, he should be capable of tracking her movements and intercepting Akua's attacks, which has been implied in chapter 43, considering the fact that Tsukune was the only one, in his group, who was capable of sensing Gyokuro's youkai energy.
After all, it's not like Tsukune has to keep up with Akua's movements, he just needs to intercept her attacks, and execute his own counterattack at the same time as Akua's attack is being blocked, letting his endurance and Determinator attribute take care of the rest of the details surrounding his fight with Akua -at least, that's the general idea that came to my mind on how Tsukune could beat Akua.
Not to mention that, it's quite evident that Tohou Fuhai has learned what Akua is capable of, during his brief fight against her in the Wong family mansion, and judging from his attitude in chapter 38 and 39, I don't think he would bother himself with training Tsukune, if he hadn't had any chances of wining against Akua.
As for the exact details on the method that Tsukune is going to use to win his fight with Akua, well we will have to continue reading this manga to find that out
