After applying the fiendish template, what creatures of the animal, vermin, and magical beast types at CRs 1, 2, and 3 (prior to template application) become the most vicious at:
Tanking?
Damaging?
Controlling?
Shutting down enemies outright?
Flanking buddy-ing?
Mobility?
Generally the most useful in the widest range of situations?
Input on any or all of these would be greatly appreciated.