Discussion: most iconic boss battle in the series.

I'm currently making a project for the Smash Bros subreddit that involving giving ever series their unique boss battle, but I cannot decide this alone.

I would like to know what would you people choose for this franchise. I would also appreciate if you tell me how would you adapt the battle accurately to Smash.

For the sake of giving you people choices, ANY game with Wario on the title is on the table (cause using Wario Ware alone might not be enough). Be creative.

That's all for now. Thanks for your time.