"Mortal Combat being to violent" is gonna be the new "Bayonetta is too sexual," isn't it?
To be fair, Mortal Kombat is most famous for its gore. Bayonetta is more than just "sexy" with what she does. Her characterization, her magical abilities, the demon stuff. These are pretty easy to incorporate. Let's not forget that Smash, since Brawl, became more accepting of darker stuff. The usual censoring is generally gone. No longer do they care about using "Devil" and stuff like that.
Mortal Kombat is still on a different level. I'm not saying it can't work, cause the ideas shown above show how easy it is to make the characters work. But the brutalness of MK characters is also important. Simply using flashy attacks isn't the same as gore/bone-breaking/etc. Bayo is more about flashy summons and such. They did obviously tone down the sexual moves to keep the rating, but the extreme attacks on MK characters are simply different. It's the impact of their attacks that matter, not simply the gore alone.
I've been a fan of MK from the first game on. So I'm very experienced in understanding the series. Simply removing the blood does not "tone down" the games. They're still brutal as hell without it. Yes, you can remove or see poorly done fatalities without blood, sure, but that's still a fatality. As I said before, though, toning them down while incorporating their infamous techniques is possible. The hard part is keeping the brutal impact of the moves intact, making them still feel like the character. That's really where the series shines. Just how deadly it feels. How much force you throw into that kick/punch/weapon attack. I will note that the very early games didn't do this nearly as much, but that's due to the gore being the focus. Once the 3D era hit, the games improved with the introduction of forceful strikes(moreso than the Uppercut/Roundhouse Kick/Boss attacks) as a focus.
So as long as Scorpion(or whomever) feels like they're still being forceful with their bigger moves(which considering there's Smash attacks, it's quite possible), the characters will feel like they fit just fine. Skeletons actually show up in the series, so his flame attacks work fine too, even a censored variation of his main fatality works. A personal suggestion for the Spear is for it to work similar to the Hookshot. Now, what does worry me is the Kunai attacks. I've outright noticed that Sakurai ignores variations of knives heavily. So that might not work. Scorpion however does have a battleaxe, as well as two swords, which seem to be specific to Hapkido users(his official style). I could be wrong on the sword part, though. No, I don't remember their proper names. Of course, his teleport punch works well, albeit, they should use the Cyber Ninja version as a Recovery(it's similar to a Dragon Punch, but he goes straight up, like Luigi's). Of course, it wouldn't actually home in on a character, except maybe if it's done on the ground, but I can tell you right now that that version is a very broken move in the MK universe. It's easy to block, but too hard to read in a less competitive game, where stuff is more telegraphed. Unless it was made slower(but maybe hurt the shield a bit more than normal), it wouldn't work too well.
...Yes, I'm a MK nerd. Sue me.