Anyway, Pikachu lost to Grapploct recently thanks to some good strategy from Bea, and that doesn't make Pikachu any weaker.
So yes, powerscaling can affect but there are many more things in a Pokémon battle. For example
The speed (Greninja, Metagross)
The Power (Charizard, Star Assault sirfetch'd)
The Aura (Lucario)
status effects
The different strategies (Grapploct, Destiny Bond)
Then,
@SerGoldenhandtheJust is rigth, we have to wait for the battle to see what Pikachu can do. maybe a grand strategy.