"Green Lizard" is a Yoshi stand-in and "Big Penguin" must be a Dedede stand-in. "Purple Dragon" is probably just a reference to the How to Draw Dragons book to throw players off but you could also joke that Spyro got into Smash in the Deltarune timeline.
Not as certain about the Sword Magician, though. One of the Fire Emblem girls was my first thought, like Robin, but she has multiple elemental tomes than just fire and can also be male. Pyra from Xenoblade probably fits the "fiery sword girl" descriptor better but I don't think she qualifies as a magician?