Ohhhh that is not good. Being Thrashed at by an Umbreon.

But isn't Hidden Power a direct damage attack?

it is a damaging attack, but after your enemy uses torment, you cant use the same attack twice in a row. if you only have one attack all you can do on the alternate turns is use struggle.

The effect of the Choice Band works when it sticks to a move your poke knows, when Ditto transforms, it no longer has "Transform" with it, so the Choice Band´s effect wont work... I think.

Now, on-topic, I say that using Taunt and Torment now sounds like a good idea if you mean to leave your opponents without PP, and it is even faster in a double battle and both of your pokes have the Ability "Pressure" ... I think I have an idea for a team now

its a good tactic in some situations. eg it is a good way to nullify some pokemon, eg standard suicune (calm mind, rest, surf, roar) or to some extent snorlax (to stop it from cursing). but there are plenty of ways to get around it. eg if a faster pokemon gets a taunt in first and all your moves are like taunt, mean look, baton pass, torment, then all you will be able to do is struggle. now theres another question. lets say you have no attacking moves and someone uses taunt. of course you have to use struggle. but then what if they also use torment. will it cause the game to blow up? or is there a second kind of struggle? maybe struggle is the only move which can be used twice in a row after torment.