Mario Series have Easter Eggs that are most common of all Easter Eggs in differing types of series created by Nintendo. They have appeared in Zelda games, Donkey Kong games, Yoshi games, Animal Crossing games, and even Banjo-Kazooie games.
In Donkey Kong Country 2, Mario appears the first Greatest Video Games Heroes who collected the most DK Coins after Diddy Kong and Dixie Kong defeat Kaptain K. Rool. To catch up with Mario and take his first position, you need to help Diddy Kong and Dixie Kong collect all DK coins in every world, including the secret Lost World deep within Crocodile Isle.
Mario also appears in Donkey Kong 64, but only when Donkey Kong accesses the Donkey Kong arcade where you must play as Mario to rescue Pauline in the first level and then the N64 coin in the second level.
In Zelda games, Mario appears as painting in A Link to the Past to release Rupees if Link pulls on the painting. Chain Chomps also appeared as Easter Egg enemies.
In Ocarina of Time, Mario, Luigi, Peach, Yoshi, Toad, and Bowser appear in pictures found inside the room to sealed with windows to the right of where you meet Zelda. If you shoot a Deku Seed at it with a Slingshot, it release a Red Rupee. In 3DS remake, they are replaced with a World 1 background in New Super Mario Bros.
In Majora’s Mask, you can see the Happy Mask Salesman carrying Mario’s Mask on his bag while in a quest to stop of the Moon from falling down to Termina.
In Link’s Awakening, you can encounter Goombas, Piranha Plants, Pokeys, Cheep Cheeps, Shy Guys, Boos, Spinies, Poodaboos, Chain Chomp characters, and Bloopers as Easter Egg enemies. Yoshi appeared in Link’s Awakening but as a doll that can be given to a specific character and begin the Trading Quest. You can also see a picture of Princess Peach mentioned in a letter that must be taken to a specific recipient during the Trading Quest. You can even meet Wart who also appeared in Super Mario Bros. 2.
In Oracle Seasons, you can encounter Poodaboos, Cheep Cheeps, and Pokeys.
In The Minish Cap, Lakitus, Spinies, and Bob-ombs appear as Easter Eggs enemies. Also, if you head a caterpillar enemy with the sword, it gets mad just like a Wiggler.
In the original Hyrule Warriors, you can unlock a strongest tier of Link Gauntlets that have a Chain Chomp as an Easter Egg.
In Tri-Force Heroes, there is an item that shoots fireballs with an Easter Egg fireball sound from Super Mario Bros. There is also an unlockable outfit that will make you look just like a Hammer Bro from Super Mario Series.
There are enemies and collectibles that you can also encounter in Metroid games.
In every Animal Crossing game, you can get clothing and furniture that belong to the Mario Series, including the Mario Theme, Big Bros’ Hat, and Li’l Bro’s Hat. However, from the Mario Theme, there is a criteria in each Animal Crossing game to get all the furniture belonging to the Mario Series.
In Banjo-Kazooie in N64, you can find a mustache face that looks like Mario’s if you enter a specific location wih the Jigsaw Piece in Gobi’s Valley while venturing in Gruntilda’s Lair to rescue Banjo’s sister, Tooty.