Dude, how come you are have Dragon Slayer level? Man I just can pass the stupid Demon Slayer... I can never pass more than 3 bosses at the last game. Are all of your characters reach level 16? Is the secret on making 1mil points in the mini games? What's the secret??? I'm going frickin crazy... I finally got Tsunami..throw me some light about stupid maelstrom. Maybe is because English is not my first language lol. Cheers bro!
It really depends on which characters you play and also playing on the first day, scoring points, to get synergy points that you can spend on later days to buff your team, then, at around 3 days in, you will be able to max out all the points and then you can do all the challenges again, scoring a high score :)