The big picture: Nintendo's Switch has smashed even the most optimistic of expectations in its first 21 months on the market thanks in part to a solid selection of franchise favorites like Mario, Super Smash Bros. and Zelda.

Super Smash Bros. Ultimate has become the fastest-selling Nintendo Switch game of all time.

Launched on December 7, Nintendo managed to sell more than three million copies of Super Smash Bros. Ultimate in the US in its first 11 days on the market according to the company's own internal sales data.

Super Smash Bros. Ultimate isn't the only game Nintendo is proud of. As Nintendo of America President Reggie Fils-Aimé shared last week, Super Mario Odyssey, Mario Kart 8 Deluxe and The Legend of Zelda: Breath of the Wild all have attach rates of better than 50 percent (meaning half of all Switch owners have these games).

In the US, Nintendo has sold more than 4.7 million copies of Odyssey and over five million and four million units, respectively, for Mario Kart and Zelda.

Pokémon: Let's Go, Pikachu! and Pokémon: Let's Go, Eevee! have combined to sell two million units while Super Mario Party has been purchased 1.4 million times in the US.

The NPD Group on Tuesday also revealed that the Switch has become the fastest-selling console of this hardware generation. In its first 21 months of availability, Nintendo has sold more than 8.7 million systems in the US, outpacing all other current-gen systems through the same point in their life cycles.