Child of Light is one of my favourite games! My strategy is to deck out each character with its own oculi combo of strengths and defenses rather than continually reequip two characters. This really helps maintain a party skill level rather than two very strong characters and a bunch of weak ones. That way, you always have someone prepared to fight each type of monster, and if someone is injured you can rotate party members and still have good fighters.
Since you've already played one of my favourite games, you might as well play the other one:
OFF Only play if you're prepared for heart breakOFF is a story-rich RPG puzzle game for PC. It's "open world" in the same sense that Child of Light is in that you can explore any part of the world you've unlocked at any time. It's an indie game with a strong fan base and has multiple endings (all with various levels of sadness). OFF isn't on Steam but can instead be downloaded for free
here. I hope you guys'll check it out!