While yeah Specs Keldeo is very threatening SpD Celebi, max HP Toxicroak, and SpD Amoonguss all shut it down easily. It is important to note that all of those threats don't mind a BandTar partner at all, as Celebi has Baton Pass, and the other two can easily stomach a Pursuit. Even if Keldeo uses Hidden Power Ghost/Ice on the switch, Celebi isn't 2HKOed by it and can simply Recover off the damage as Keldeo switches out, Amoonguss can just switch out on everything to take the locked HP having lost only 20% net damage (it's not hard at all to get Amoonguss in again and switch out to heal the 20%, before Keldeo comes in again), and Toxicroak can simply use Drain Punch on whatever comes in and heal back to full health (in two turns Toxicroak will have healed 18.75% + 18.75% + ~10% from Drain Punch, which is exactly the amount of damage that Keldeo did with Hidden Power).