Ok... so one after another
Adult Dragon - I'd make them stationary actually. Adult dragons can fly, but they mostly sit on a pile of treasure (there should be some cash for beating one) and attack those who get too close to it.
Bat Mob - again, I don't think they count as monsters, unless you feel we really need them
Bear - do you have any pic of the really bad bear you spoke of? Remember we still have ursa minor to use
Cerberus - why is he endless? (obviously, the series didn't give us an opportunity to see if he is immortal
Changeling -ok
Cockatrice - it flies like a hen. I'd give it stalker movement
Hydra - might be aquatic. I don't know if it deserves ambush - running away from it is exactly what they did.
Manticore - it is very buff and probably not a good flier, but we can leave it like it is.
Mind Slave - ok
Quarray Eels - I'd give them overwhelming - they are huge and fast enough to snap at creatures flying near their lair
Squid - again, I think it's not a monster. If you want an aquatic monster, use an alligator instead
http://images.wikia.com/mlp/images/f/fd/Scootaloo_about_to_get_onto_the_alligator_S3E06.pngSunset Shimmer - I'd drop her for now. She will probably end up as either a blight or a herald.
Teen Dragon - ok
Timberwolves - ok
Cave troll - ok
giant spiders - I'd replace overwhelming with ambush
vampiric jackalopes - ok
chupacabra - ok (remember it will fight the jackalopes if they end up in the same field)
pony-eating petunias ok
Timber wolf king - what makes it elusive? does it represent the fact that the wolves combine only when they attack someone, so you wouldn't find it otherwise?
