regarding dark teams pretty sure most ragnaroks will be clearable with a team consisting of arthur (sniper shot), SSR amon, satan, hades and SR beelzebub. 2 SSR defender weapons and rest maxed skill lvl assault weapons. personally i'm aiming for something like amon, susanoo, hades and osiris, the next event will be really important as the SSR axe is required for arthur and the eidolon is useful for the next advent ragnarok.

youtube watch?v=hSh47nAdDO0 (can't post links) it's the next advent ragnarok with dark team