Well Elesa's Pokemon are Emolga level 28, Flaafy level 28 and Zebstrika level 30
Emolga has Quick Attack, Volt Switch, Pursuit and Aerial Ace
Flaafy has Thunder Wave, Confuse Ray, Take Down, Volt Switch
Zebstrika has Flame Charge, Volt Switch, Quick Attack and Stomp
Your best best (only bet really) is Roggenrola to win. Dewott and Tranquill will get completely destroyed by Volt Switch and Leavanny gets killed by Flame Charge and Aerial Ace. You could use Leavanny to beat Flaafy, but apart from that your team is kind of outclassed.
To win with your curretn team, make sure to train Roggenrola as well as possible since it's basically going to be soloing. Alternatively just completely overlevel and you'll be fine. xD