OBJECTION! ... What about Palutena's guidances? It's the only thing related to a plot! Ganondorf can be considered alive due to the fact there's probably an unfinished Zelda timeline in which Ganondorf is still alive in. Medusa... doesn't have such importance, unlike Ganondorf which has appeared in a lot of games (considering Medusa's identity in the first KI is just "evil giant snake lady", unlike her identity in Uprising).
I'll be fine with it. Unlike Ganondorf, which can't be actually dead due to the fact that the Legend of Zelda are still JUST LEGENDS, Medusa is actually dead.
Let me say this:
If Sakurai wants to add Medusa, he'll bend his headcanon called Uprising to fit.
Just like he fanfic'd Dark Pit in the Forces of Nature and called the Lightning Chariot back in existence after it was destroyed.
Sakurai is the creator of the KI-mythos and as we have seen he's not afraid to spice it up with a bit sequel bait and Word of God.
Fixing this problem is as easy as saying Medusa followed an online "Revival for dummies" course.
It's not like Kid Icarus itself takes itself serious.
Constant four wall breaking and inside jokes.
If you want an actual explanation, go the Zelda route and say "LOL gods r immortal duh"
Sakurai has the power to do that.
Wait......
If you die in the Greek Mythos, you go to the Underworld.
And since Kid Icarus aren't just legends and has a super strict canon lore, Medusa can still be in.
Oh wait. KI is based on the Greek Mythos.
JUST LEGENDS.
Ganondorf is based on his Twilight Princess form, which is dead. There.
Medusa has other problems, but "being dead" isn't one of them.
Now other examples of Smash Bros. not caring about lore, canon or logic:
-Dr. Mario/Mario existing in the same battle, each cloned four times
-Same with Link/Young Link
-Ganondorf. He's a powerful, earth shattering and dead warlock in Zelda. Not in Smash.
-Toon Link being able to fight Twilight Princess Link on Skyloft.
-Skyloft's stage taking place in the middle of Skyward Sword.
-Mario fighting Pikachu and Pac-Man with four clones at his side.
EDIT: Daisy X Medusa OTP.
there its ontopic now.