If we get an Echo Fighter Pass, I would expect five new fighters. I would also expect one difference for each fighter. Here's the list. Sorry if my list feels the same as most others.
Bowser - Midbus: Instead of fire attacks, Midbus would have ice attacks. His Final Smash would be Blizzard Midbus.
Diddy Kong - Dixie Kong: Instead of the Rocketbarrel jetpack, Dixie Kong would fly with her hair. Final Smash Undecided.
Sonic - Shadow: Slightly slower, and uses Mewtwo teleport as a recovery move. His Final Smash would be Eclipse Cannon.
Pikachu - Raichu: Faster, heavier, and harder hitting. Neutral Special changed to Thunderbolt. Final Smash is still Volt Tackle.
And finally...
Palutena - Medusa: Slower and Heavier. Would use dark versions of Palutenas Attacks. Her Final Smash is Stone Gaze.
So wh did you think? Comment below... maybe?