When Lightning Strikes
From SmashWiki, the Super Smash Bros. wiki
When Lightning Strikes is a single-player event match in Super Smash Bros. for Wii U. The player controls a small Pikachu, and must defeat 3 giant-sized Pikachus. The player can collect Lightning Bolts to shrink the enemy Pikachus for an easier KO. Clearing this event will unlock Pokémon Stadium 2.
This event is unlocked by clearing King of the Yoshis. Completing the event unlocks the Pokémon Stadium 2 stage on the challenge board, but does not unlock any additional paths. Once both the event is completed and Wario is unlocked, the right path is unlocked.
Completing the event on normal or hard difficulty within 60 seconds awards an Unharmed Attacker X Defense equipment.