How should I go about playing a game like this?

My team is Thresh support, Rumble top, Fizz mid, Ezreal adc, and me as Elise in the jungle.

Their team is Ashe adc, Jayce mid, Alistar support, Sejuani Jungle, and Quinn top.

So when this match actually happened we mopped the floor with them, but I feel it was because they were fighting and arguing among each other, and just kinda not trying mid-late game anymore after our fizz got a mejas with full stacks. Their really wasn't too much 5v5 team fighting either but, I feel like their team fight would have been a lot stronger if they weren't tilted or had done something right early game. I guess what I'm really asking is:

• How should someone play around a team that has a better team fight potential?
• How would I out jungle sejuani as elise?
• Why is Fizz's sprite still a light blue square (inb4 new icon for rework)
• And any other notes you might have about it.