Bronto/Mummy/Barn owl vs Elephant

Does using both types of pets help add more weight or do the weight hatching pets just get you to a higher base faster and then the elephant just tops it up according to max base stats?

I’ve been trying to find info on the synergy between these weight boosting pets and having a tough time.

Hoping someone could answer here?

I want to know if it’s worth keeping all these extra pets when I already have an elephant and a good level up team.