Kaidou, as in, healing kido, but fair enough I guess. Though being a lieutenant/seated officer, she had to be good at something, and I kinda doubt she's a sword, hand-to-hand, or flash step fighter.
She didn't have to be good at anything.
Being a Vice Captain just depends on reiatsu level.
If you're strong enough, you will be recognized and promoted. Even between divisions. Renji was promoted from 6th Seat of the 11th to 2nd Seat of the 6th and he had no specific talent