Well because I'm not familiar with Mercy and spec. I can say that wonderwoman and if she needs help starfire could beat she-hulk, Ms. Marvel, And Namora by herself/themselves.
Mercy:
Flight
Intangibility
Invisibility
Teleportation
Shapeshifting
Energy projection_in spear form
Telepathy
Astral projection
Extrasensory perceptions
Spectrum:
Can convert body into any form of energy within the electromagnetic spectrum. Energy generation, absorption, intangibility manipulation.
Travel at speeds up to the speed of light while in her energy form.
Able to travel in energy form through the vacuum of space.