As boss pets are super rare, they should be given special abilities from each boss as attacks, so that they can do damage.
This would bring a big variant to summoning, as Steel titan wouldn't be the only best option as pet for PvM.
It would also motivate people to do more bosses in order to achieve better boss pets.
This would also be a huge change and distinction from any other servers out there, bringing more players in.
As long as they are not too overpowered, but as well better in dps than regular steel titan (which is easily obtainable throughout skill) also requiring summoning lvl to be used, this should work very well!