Here's my idea, Cyber-Vanellope
Plot: 5 years after the last movie, Sugar Rush starts glitching out and becomes a post-apocalyptic world because Vanellope is missing from the game and is not there to lead them. As she hears about this, Vanellope must journey back to the arcade to save her game from getting unplugged, while facing even bigger threats that come her way...
List of cameos
MDHR studios - Cuphead, Mugman, Captain Brineybeard, Goopy le Grande, Devil, King Dice
Sony - Crash Bandicoot, Ratchet, Clank, Jak, Daxter
Nintendo - Rosalina, Zelda, Kirby, Link, Meta Knight, Cappy, Bowser Jr, Donkey Kong
Scott Cawthon - Freddy Fazbear, Coffee Pot, Souldozer
Don't forget Spyro the Dragon, Battletoads and King Dedede.