I wasn't a huge fan of the costume Teddy wore in that Children's Crusade special, it was a bit plain, but I did think it was on the right track. Using his own appearance instead of shapeshifting into a fake Hulk seems like a more mature direction for the character.
If he were to embrace the Mar-Vell legacy then I say give him the Ultimate Mahr-Vehl armor. It had its own shapeshifting properties that I think would mesh well with Teddy's abilities, showing an acknowledgment of his Skrull lineage. Replace the planet symbol with the Hala star.
I'd redesign it a bit with the green and black/starfield color scheme that Genis used for a while. It's a call back to to the classic Kree soldier colour scheme, but distinct enough to stand out on its own. The green is a good color to use to represent both the Kree and Skrull, and if he were to shapeshift in his trademark wings then they could match the armor. And the starfield lets him match with Billy.
Plus the whole futuristic Greek soldier design thematically fits with his space broadsword Excelsior.