Elesa will keep using Volt Switch on you, so you need to be at a higher level than you are now in order to take the damage. Emolga is at 26 (if you're talking about B2W2) and Zebstrika at 28. If you Growlithe has Flash Fire, it will be perfect to deal with Zebstrika. Intimidate will also work because Zebstrika relies on physical attacks (except Volt Switch). Like it was suggested below, get a Sandile (the most readily available ground type) which means that Elesa can't Volt Switch/ Thunderwave you into oblivion.
The reason you're stuck is because you relied too much on one Pokemon (happens to me with my starters) and breezed through everything to get the next gym ASAP.