I think that people are beginning to overthink the concept of echoes, and as a result lose touch with realistic echo character possibilities.
One thing I notice is that people tend to look for any slight similarity between any character currently in the roster and a “potential echo” and immediately consider that echo “likely” due to said similarities, no matter how far a stretch it actually is. Giygas as a Mewteo echo comes to mind...
Sakurai’s team isnt just going to start slapping echo characters in because the character slightly looks or plays like another one. What I believe is that the Echo Character spots are saved for characters who are at least somewhat popular, but not quite popular enough to justify putting in the time to create an entirely new character out of them. Therefore, they’re made into echoes, so that they can still be put into the game with only a fraction of the time needed to develop them.
I also think that cross-series echo fighters isn’t going to be a thing. Yes, we had Ganondorf in Melee, but Sakurai stated himself that Ganondorf barely got in. Making him a Falcon clone was an afterthought. No reason to believe that’s going to happen again. Besides, I haven’t seen a single cross-series echo suggested that wasn’t in some way a stretch.
If it makes sense for the character and they're similar enough, why not? Ganondorf was a different matter since he's such an iconic character with his own skillset to pull from the source material and they just slapped him on a slower Captain Falcon. Something like, I dunno, Dr. Eggman over Bowser Jr makes more sense since they both use flying mech pods and gadgets.
Not saying I WANT Eggman to be a BJ echo (give him his own moveset!) but it's a good example.
Eh, I wouldn’t consider that a good example. In fact, I’d consider it a stretch. You’re right that they both have the mechs and abilities that are similar, but the proportions are WAY off.
I hate to use the size argument after Ridley got confirmed, but this is different. The thing about Ridley is that he is still one of the biggest characters, most importantly, bigger than Samus. Bowser is bigger than Mario, too. Bowser Jr., however, is smaller than Sonic (his model alone, not the clown car). That would be one tiny Eggman.
Regardless, Shadow is the much more obvious choice for a Sonic Series echo. He’s more popular, is similar in both shape and stats to Sonic, and was even presented in his debut game as an alternate Sonic... an “anti-Sonic.”