For positive CR all I have for an instant effect would be Yuuri! He's not part of the Watch, but he helps out in the clinic if Dave ever needs to be stitched up or something?

As for negative CR, there's Sephiroth and Yuri Petrov on my list (although Yuri is harder to gain negative CR since there needs to be certain conditions xD)

Also, for neutral I just have a ten foot tall telepathic alien >_>