"Battle! (Regirock/Regice/Registeel) - Pokémon Black & White 2" is a high quality rip of "Battle! (Regirock/Regice/Registeel)" from Pokémon Black & White 2.
Joke[]
At 0:20, the lead melody is played by an extremely loud trumpet instrument, in particular the kind that was infamously overused in the Generation 3 Pokémon games. The lead is off-sync with the advertised track.
This is possibly a throwback to the "Underground Ruins - Pokémon Black & White 2", given the joke is the same and the event this rip was uploaded during.