Back in the day before Sword and Shield were released, the demo from E3 had a slightly different gym leader battle theme than the one we are familiar with today. Back then, it was extremely hard to find a good quality video featuring the track without any surrounding noise. Thanks to the recent beta leak for Sword and Shield, the beta gym leader theme was posted and contained "the missing part" (0:59 1:27). I have pieced the two together so that you can hear what the demo version was actually like. It's not perfect, but it is much better without the background noise. Hope you enjoy!

Original Part was from Bakugo:    • Pokémon Sword & Shield OST  Gym Lead...  
Missing Part was from Thegamingxpert:    • Pokemon Sword And Shield: Beta Music ...