When forming a team, a general priority for a balanced team is as follows (should be mostly same-element):
Healing (up to 500 HP/round) > Debuffs (mainly ATK and DEF DWN, get these as close to the -50% cap as possible) > Spike Damage and active abilities (sufficient to reduce the Rage Bar from full to 0 in one turn, or otherwise greatly mitigate or avoid Rage Overdrives)

A balanced team like this that meets all three criteria should be capable of completing most content.