Some Pugs can be aggressive. If an animal is not trained to understand humans as its own kind and obedient to the commands of those humans then it is likely that they will attack or display aggression.
Pugs are typically sweet, gentle animals but despite their small size, can be a handful if not trained using consistent training methods. Training a pet includes a healthy balance of discipline and reward so that they know what behaviors you want from them and how you expect them to behave in your presence.
It’s always better to have more than one animal at home because they provide companionship for each other as well as mental stimulation which reduces boredom which encourages behavioral problems such as chewing furniture or digging holes in the backyard…