Bisasu is going to appear on the 4th Pokemon movie. You can read more about the movie in my "Pokemon movies info". I don't know what is going to be his US name but his Japanese name loosly translates to "vicious".
Bisashu is also an elite Team Rocket member, but from the future, and he is vicious and brutal. In the movie he goes after Celebii, the rare Pokemon, and even travels in time in order to capture it. He almost did, with a special Pokeball that turns every Pokemon that's caught in it evil. Bisashu is in love with Jessie and he kidnapped her in the movie and held her hostage.
Bisasu is planning to be the leader of Team Rocket, and the assumption is that he wants to be the future leader after Giovanni, even though when his mask breaks, he looks like Giovanni.
