See one of the post why Baton Pass was moved:
The OU Council believes that Baton Pass, as a move, should be banned from the SM OU metagame. Despite having a clause implemented to hinder Baton Pass teams, there are clearly still effective teams that make use of this strategy. Baton Pass teams are one of the most controversial parts of the metagame currently and this is in large part due to the strategy behind them, passing stat boosts to threatening Pokemon that can take advantage of them without many drawbacks. Common abusers of this strategy, such as Necrozma, Magearna, and Espeon, take advantage of being passed Speed boosts from Scolipede and then set up on their own, proceeding to sweep through a significant portion of the metagame and teams that are used. Therefore, the OU council believes that these teams have no place in the SM OU metagame and we must do something to change this.
As you can see, Baton Pass is banned in these format, except for Anything Goes. Baton pass is not banned only for Absol; no Pokemon can use Baton Pass because it is too overwhelming, that's why Smeargle is (PU), while it should be Ubers since it gets Spore and Shell Smash.
