Mario Kart 8 Deluxe update adds 5 more extra character slots beyond Birdo

It would appear that Nintendo will include six new characters into Mario Kart 8 Deluxe

Mario Kart 8 Deluxe 'Booster Course Pass' Wave 5 launches July 12 - Gematsu

Mario Kart: Double Dash!! Walkthrough - GameSpot

Mario Kart 8 Deluxe Getting Five More Characters in Future DLC Waves - IGN

Mario Kart 8 Booster Course Pass: Yoshi Island and Birdo being added as DLC, Page 2

Five more characters coming to Mario Kart 8 Deluxe expansion pass

Mario Kart 8 Deluxe's Character Menu Now Has Five Extra Spaces For Future Updates

Mario Kart 8 Booster Course Pass: Yoshi Island and Birdo being added as DLC, Page 2

Dixie Kong's Barrel Of Support Spirits. Farewell Everyone, Thank You ALL For Making This Thread An Excellent Place For DK Fans!, Page 163

Mario Kart 8 Deluxe Wave 4 Update Brings Balance Changes And Five New Character Slots - Gameranx

Mario Kart 8 Deluxe Booster Course Pass Wave 4 Review (Switch eShop)

Squid Dude The Squid Chamber

It Looks As Though Diddy Kong Has Been Confirmed For Mario Kart 8 - My Nintendo News

Lists The Squid Chamber

Mario Kart 8 Deluxe Wave 4 Update Brings Balance Changes And Five New Character Slots - Gameranx

Mario Kart 8 Deluxe Booster Course Pass Wave 4 Review (Switch eShop)