Is Giovanni's Shadow Pokemon reward dependent on the month or the quest?

Solution 1:

The shadow legendary Pokémon Giovanni has is based on the month, not when you received the quest. So you would get another Suicune and not Articuno.

It does not matter how you obtain the Super Rocket Radar (whether it be from the Looming in the Shadows or the Go Fest challenges), you will battle and catch the last legendary Pokémon Giovanni was in possession of.

When the Looming in the Shadows quests were active every month, I missed the first three months and never was able to complete the quest. When I was finally able to defeat Giovanni for the first time in February 2020 with the original Looming in the Shadows quest I received in November, the legendary reward was Raikou.

This happened again a few months later. When I completed the Looming in the Shadows for Feburary, I received the quest for March but was unable to complete the quest until May. While the quests were temporary discontinued in April, I received March's reward for completing it May (that reward being Entei)