Check the Johto region restriction
Only Johto League members count toward the member threshold. Kanto members do not substitute for them. Challenges that specify Johto companions must also be completed with Johto companions.
Check Celebi’s own requirements
Celebi’s League challenge lists the Johto member threshold and the Hard Shrine of Time battle. It does not list capturing the three beasts as a prerequisite.
When looking for the Shrine of Time entrance, match the English location name with the current map and event instructions.
