Kamui fks all of em' 
Gintoki and Takasugi are nearly equal.
And as Umibozu and Hosen were once even and since both have aged may have had weakened. Gintoki won vs Hosen only because of Hyakka's repeated interference, a cheap shot and the sun. Otherwise, Gintoki would have died at least 3 times while Kamui fought Hosen on equal terms. Even then, I believe he was holding back...