Sonic/Mario

Version 1

 * Sonic as Mario
 * Knuckles as Luigi
 * Tails as Yoshi
 * Amy as Birdo
 * Sally as Princess Peach
 * Bunnie as Princess Daisy
 * Big as Pianta
 * Shadow as Wario
 * Silver as Waluigi
 * Rouge as Candy Kong
 * E-123 Omega as Petey Piranha
 * Espio as Chunky Kong
 * Charmy as Diddy Kong
 * Vector as Donkey Kong
 * Dr. Robotnik (AOSTH)/Dr. Eggman as Bowser
 * Scratch as Lemmy "Hip" Koopa
 * Grounder as Iggy "Hop" Koopa
 * Coconuts as Larry "Cheatsy" Koopa
 * Robotnik Jr. as Morton "Big Mouth" Koopa
 * Breezie as Wendy "Kootie Pie" O Koopa
 * Snively as Ludwig "Kooky" Von Koopa
 * Bark as Roy "Bully" Koopa
 * Dr. Robotnik (SATAM/SU) as Smithy
 * Dr. Quark as Popple
 * Doofus as Rookie
 * Chris Thorndyke as Oogtar
 * Rotor as Toad
 * Cream as Toadette
 * Uncle Chuck as Toadsworth
 * Maria Robotnik as Princess Rosalina
 * Metal Sonic as Bowser Jr.
 * Mighty as Red Yoshi
 * Ray as Yellow Yoshi

Version 1.5

 * Sonic as Mario
 * Tails as Yoshi
 * Shadow as Luigi
 * Sally Acorn as Princess Peach (some games) or Pauline
 * Bunnie as Princess Daisy
 * Amy Rose as Princess Peach (some games) (Amy cannot be Birdo because Birdo was never in love with Mario)
 * Cosmo as Birdo
 * Knuckles as Wario
 * Rouge as Candy Kong
 * E-123 Omega as Petey Piranha
 * Dr. Eggman as Bowser
 * Chris Thorndyke as Oogtar
 * Rotor as Toad
 * Cream as Toadette
 * Uncle Chuck as Toadsworth
 * Vector the Crocodile as Donkey Kong
 * Charmy Bee as Diddy Kong
 * Espio the Chameleon as Shy Guy
 * Maria Robotnik as Princess Rosalina
 * Metal Sonic the Hedgehog as Bowser Jr.
 * Mighty as Red Yoshi
 * Ray as Yellow Yoshi

Version 1.6

 * Sonic as Mario
 * Tails as Yoshi (So Tails can't be Luigi)
 * Mighty as Luigi (So Mighty can't be Yoshi)
 * Amy Rose as Princess Peach
 * Blaze the Cat as Princess Daisy
 * Breezie as Birdo
 * Chip as Toad
 * Knuckles the Echidna as Wario
 * Silver the Hedgehog as Waluigi
 * Dr. Eggman as Bowser
 * Chris Thorndyke as Oogtar
 * Uncle Chuck as Toadsworth
 * Vector the Crocodile as Donkey Kong
 * Charmy Bee as Diddy Kong
 * Espio the Chameleon as Shy Guy
 * Maria Robotnik as Princess Rosalina
 * Metal Sonic the Hedgehog as Bowser Jr.
 * Mighty as Red Yoshi
 * Ray as Yellow Yoshi
 * Scratch as Lemmy "Hip" Koopa
 * Grounder as Iggy "Hop" Koopa

Version 1.7

 * Sonic the Hedgehog as Mario
 * Shadow the Hedgehog as Luigi
 * Miles Tails Prower as Yoshi
 * Amy Rose as Princess Peach
 * Blaze the Cat as Princess Daisy
 * Breezie as Birdo
 * Chip as Toad
 * Knuckles the Echidna as Wario
 * Silver the Hedgehog as Waluigi
 * Dr. Eggman as Bowser
 * Chris Thorndyke as Oogtar
 * Uncle Chuck as Toadsworth
 * Vector the Crocodile as Donkey Kong
 * Charmy Bee as Diddy Kong
 * Espio the Chameleon as Shy Guy
 * Maria Robotnik as Princess Rosalina
 * Metal Sonic the Hedgehog as Bowser Jr.
 * Mighty as Red Yoshi
 * Ray as Yellow Yoshi

Version 2 (by StarFleet)

 * Sonic as Mario
 * Knuckles as Luigi
 * Tails as Yoshi
 * Amy Rose as Princess Peach
 * Cream as Princess Daisy
 * Rouge as Birdo (both have similar voice pitches)
 * Big as Pianta
 * Maria Robotnik as Princess Rosalina
 * Vector as Donkey Kong
 * Espio as Shy Guy
 * Charmy as Diddy Kong
 * Mighty as Red Yoshi
 * Ray as Yellow Yoshi
 * Dr. Eggman as Bowser
 * Grounder as Wario
 * Scratch as Waluigi
 * Coconuts as Bowser Jr

Version 3 (By PrimeThomasFans)

 * Sonic as Mario
 * Knuckles as Luigi
 * Tails as Yoshi
 * Amy Rose as Princess Peach
 * Princess Blaze as Princess Daisy
 * Cream as Birdo
 * Rotor as Toad
 * Grounder as Wario
 * Scratch as Waluigi
 * Coconuts as Bowser Jr.
 * Dr. Robotnik as Bowser
 * Antoine as Oogtar
 * Chuck Thorndyke as Toadsworth
 * Vector as Donkey Kong
 * Charmy as Diddy Kong
 * Espio as Chunky Kong
 * Bunnie as Princess Rosalina

Version 4

 * Sonic as Mario
 * Shadow as Luigi
 * Silver as Dr. Mario
 * Tails as Yoshi
 * Knuckles as Wario
 * Rouge as Pauline
 * E-123 Omega as Peta Piranha
 * Amy Rose as Princess Peach
 * Cream as Princess Daisy
 * Big as Pianta
 * Chunky Kong as Espio
 * Diddy Kong as Charmy
 * Donkey Kong as Vector
 * Dr. Robotnik as Bowser
 * Scratch as Lemmy "Hip" Koopa
 * Grounder as Iggy "Hop" Koopa
 * Coconuts as Larry "Cheatsy" Koopa

Version 5

 * Sonic as Mario
 * Tails as Yoshi
 * Knuckles as Wario
 * Jet as Kamek
 * Wave as Kammy
 * Storm as King Boo
 * Dr. Robotnik as Bowser
 * Scratch as Lemmy "Hip" Koopa
 * Grounder as Iggy "Hop" Koopa
 * Coconuts as Larry "Cheasty" Koopa
 * Robotnik Jr. as Morton Koopa Jr.
 * Shadow as Luigi
 * Silver as Dr. Mario
 * Rouge as Candy Kong
 * Petey Piranaha as E-123 Omega
 * Amy as Peach
 * Cream as Daisy
 * Big as Chunky Kong
 * Espio as Funky Kong
 * Charmy as Diddy Kong
 * Vector as Donkey Kong
 * Vanilla as Candy Kong
 * Metal Sonic as Bowser Jr.
 * Wisps as Lumas

Version 6 (ZacharySwainGood1)

 * Sonic as Mario
 * Tails as Yoshi
 * Shadow as Luigi
 * Silver as Dr. Mario
 * Knuckles as Wario
 * Amy Rose as Princess Peach
 * Rouge as Birdo (both have similar voice pitches)
 * Blaze as Princess Daisy
 * Lucas as Waluigi
 * Vector as Donkey Kong
 * Doctor Eggman as Bowser
 * Scratch as Lemmy "Hip" Koopa
 * Grounder as Iggy "Hop" Koopa
 * Coconuts as Larry "Cheatsy" Koopa

Version 7

 * Sonic as Mario
 * Rotor as Luigi
 * Tails as Yoshi
 * Rouge as Birdo
 * Amy Rose as Princess Peach
 * Princess Sally Acorn as Princess Daisy (they're both princesses with brown hair)
 * Charmy as Toad
 * Cream as Toadette
 * Knuckles as Donkey Kong
 * Shadow as Wario
 * Silver as Waluigi
 * Dr. Eggman as Bowser

Version 8

 * Sonic as Mario
 * Knuckles as Luigi
 * Amy as Peach
 * Rouge as Daisy
 * Charmy as Toad
 * Cream as Toadette
 * Tails as Yoshi
 * Cosmo as Birdo
 * Dr. Eggman as Wario
 * Shadow as Bowser (both are evil looking and have no real love interests)