What is the dumbest thing you've done in a pokemon game?

I don't always like spending large amounts of my stardust in Pokémon GO.

Until one day near the end of Dual Destiny, I used all my stardust to power up my Reshiram until I didn't have enough candies.

Thank god I did many battles in DD because when the season ended, it granted me all that stardust back. But my Reshiram is now my strongest Pokémon and both I regret and also don't regret spending all my stardust on it. Because life was hard without any stardust.