@Oaghaji huh I didn't know about this game before, maybe I should give it a try one day.
The reason why everything is a "smash clone" though is because smash was just more popular by way of it actually receiving a western release and being a home console game. The majority of the world would have no idea this game even existed until the internet and arcade emulation became more widespread. I mean, we don't/didn't call classic FPS games Wolfenstein clones, it's a DOOM clone because DOOM became way more popular and infamous.
There are also some marked differences, like Smash using 3D instead of 2D, a rising percentage system instead of normal health, 4 player mode and a single player adventure, etc. Idk exactly how Outfoxies plays but just judging from videos it looks like it doesn't have stuff like fast falling, or directional influence either. The objective isn't to knock your opponent out of the stage but to reduce their health to 0 instead.
If Smash was inspired by Outfoxies, I think it changed/added enough and has more refined gameplay options with more clear visual design. An Outfoxies clone would play a lot different than a Smash clone would so I think calling all of these platformer fighters "smash clones" is more apt.
It is kind of funny though, that Smash came full circle to be developed by Bandai Namco.