The wolf and bear are extremely powerful. The dog not so much. It has around 20 life and only does 5 damage. The wolf has a lot more life, I'm not sure how much, and it attacks at least 2-3 times per turn doing around 10 damage per attack. As a result, it becomes extremely damaging. The bear is slower than the wolf. It attacks once per turn but does 20-25 damage. It also has a huge amount of life, I haven't seen a bear die yet. What people do to is create tons of new accounts until they find a brute with a bear or wolf. This gives their brute a huge advantage from the get go.
For weapons its the whip and scourge. The whip does normal damage but it is extremely fast and accurate and you can often attack 3 times in a turn doing 10+ damage per turn. Also, you have a higher chance to block enemy attacks or counterattack them as well with a whip. The scourge is a slower 1 hit per turn weapons but it is still relatively accurate and it does a huge amount of damage, often 45+ for each hit.
Supers and Specialties:
6th Sense is a good specialty to have. It allows you to attack first in battle and also give you a higher chance to block or counterattack your enemy.
Tragic Potion allows you to use a potion that adds 35 health back with no loss of your turn.
Thief is a very useful skill that allows you to secretly take an opponents weapon and use it against them.
Skills that can stack on top of each other such as Untouchable and Shield are very difficult since they both give bonuses to blocking an opponents attack. Either one of these combined with vitality or immortality would be a good combination. However, since supers and specialties are acquired randomly its difficult to choose what direction you want your brute to go. As with pets, people create tons of characters in attempt to get one that has a good starting skill.