OK you 2 in an attempt to continue enjoying this game so either of you have any tips for this poison floor boss I'm sure I'll be there soon
Honestly don't know how to guide you through Poison Floor Boss 'L' ('L' being the first letter of the boss' name). It has been too long and I felt that I was still over-leveled during that fight (It was so perfunctory that I didn't notice the poison floor until after the battle). So, maybe some grinding?
I was playing Melia for the majority of the end game as she does amazing damage in the hands of the player (the computer very not so much). If you're having a tough time in bosses, I would suggest changing characters to be more focused on killing rather than survival. If you haven't already, try benching Sharla for characters with light healing such as Shulk, Riki, and Melia. Then try stacking offensive characters such as Dunban, Shulk, Melia, and possibly SEVENTH. You might discover being able to kill faster is the path to success.
I do recommend to trying out Melia. Her auras and elementals are unique and bewildering, but do massive amounts of damage when learned. Key points are that you discharge your last summoned elemental and the lightning/thunder elemental is the one that hits like a truck.