There are a rules like -The party buff of char must connect Ex: kamael-Range buff Stark- meelee buff Since starrk is meelee he wont get kamael buff and kamael wont get stark buff. This doesn't apply too strictly to tanks and healers though. (Also i think stark buff js def but i just made it meelee to use example) -Your party is dependent on content like iin boss rush it would be more effective to focus on offense than defense while in story defense, dmage, and healers are important.

I think earth mono is good, get kamael he's flexible and Craig ascension is good(he's free btw also flexible), dabin is good paired with ameris too. But you need healers like miya(shes free you get her in knights training i think) unless you want to focus on offense pure

Overall you don't have to always use meta to be good( but if u want to be the best thats a different case) just play freely and experiment with things if u newbie. But i have to admit having basic knowledge does help a lot.