Once you beat Ampere, the stage is finally lit up, with a triple spotlight coming down on Elesa in her fur coat and other accoutrements.  Head on up for your battle for the Gym badge.  Elesa welcomes you to the stage, and goes on a moment about ‘whose star shines brightest’.

Battle: Gym Leader Elesa (3200 Poke, Bolt Badge, TM 72 Volt Switch)
Opponent: Emolga Lv 28, Flaaffy Lv 28, Zebstrika (Sitrus Berry) Lv 30
Item: Hyper Potion

Elesa opens up by bombarding you with Volt Switches between her Emolga and Flaaffy, and keeps it up for some time, so have something on hand that’s at least resistant to the electric attacks.  You can force her to swap to her Zebstrika, but that’s really not an improvement- it uses Flame Charge to clear out anything Grass in the way, then she goes right back to Volt Switching like mad since it can do that also.  Immensely defensive pokemon, or something Ground-typed, are pretty much your only ways to slow her down, and with Volt Switch’s high power of 80 compounded by STAB she can put some ruinous holes in your team as you try to hand back damage.  If you can manage to fend your way past interminable Volt Switch and Static paralysis, you may actually be able to endure and outlast, likely thanks to a stockpile of healing items.

On defeat, Elesa gives you your badge and the TM for Volt Switch.  Volt Switch is a kind of mirror of the older move U-Turn.  While it’s a Special Attack move and Electric-type, as opposed to U-Turn’s Physical Attack Bug-type, the effect- swapping the pokemon out after it attacks- is the same, and can make battles very difficult for your opponent.  Finally done with the facesmashing battle, you have your badge, so it’s time to go.

Elesa stops you on the catwalk, though, and asks you to walk along with her and the Gym trainers.  At the end of the catwalk, she professes her belief that you’re exactly the kind of trainer who can and should challenge the Pokemon League and become Champion.