It srsly needs an option to switch out the starter cards once, It's kinda unfair to loose often because you had choosen the wrong starters. And you can't really guess which cards are good starters and wich are not without having ever played the game.
The main difference in the fights between Sonny 1 and Sonny 2 is mainly that the enemies have no endless supply of focus, that makes survival tactics much more valuable and the fight against some enemies much less frustating (against enemies which can heal themselves)