Can you bring smaller dogs into the pet store upstairs? (just to that one store)

Yes

You are allowed to bring dogs into the mall only from Entrance 4 to the CoolDog-gear only. All dogs must be on a leash at all times. Dogs are not allowed in any other store or other parts of the mall without special permissions.

When did they get a pet store??

No dogs are allowed

I'm not sure, but I would contact guest services or the particular store for an answer.