What happens if Klefki with "Mischievous Lock" and Empoleon V with "Emperor's Eyes" Ability somehow both become active at the same time, like at the start of the game?
If Abilities activate at the same time, the Abilities of the player whose turn it is activate first.
Source: TPCi Rules Team (2023-04-06)

Relevant cards

Note: All applicable cards may not be listed below.
SWSH5_40
SWSH5_40
SV1_96
SV1_96