ATLAS
Atlas and Atom Smasher have similar power sets. AS joined BA to work out his anger issues. Atlas would join Namor because he’s always at his best when someone else calls the shots, be it Nefaria, Zemo, or even Hawkeye. As a Defender Atlas would re-focus as the team’s big man.
QUENTIN QUIRE
Like Brainwave for BA, Quentin Quire would be Namor’s young smart mouthed psionic attack dog.
THE GRIFFIN
Griffin and Namor have history going back to John Byrne’s old book. Namor would pull him in to fill out his team. Like Northwind Griffin has that winged non-humany deal going on.
GHOST RIDER
GR/Robbie Reyes, like Eclipso/Alex Montez is a young Hispanic man fighting for control of his body w. a powerful demonic force.
ECHO
Similar power sets here, between Echo and Nemesis; photographic reflexes in this case. Both serve the same purpose on their teams as the badass mostly normals/stealth characters.