I should have talked about this months ago, but my answer is...............yesn't
For one hand, I love Simon in Smash. I love his animations, i love his design, i love his moveset. Simon could have been the ONLY CV representative in Smash, and i would have been completely OK with that, since i was pushing for Simon and ONLY Simon and never asked for anyone else in Smash. Simon was my choice and always will be my choice.
But, i do see the argument that most Belmonts basically play the same, so brining them over would have been nice. The problem is, that almost all of them have varyingly different designs. I think part of the reason they went with Richter's classic look is because they didn't have to worry about having his coat, so that already puts out the likes of Julius and Juste. Then you have to realize that since Sakurai could only give Hero 4 different alts, it's fair to say the same would be done with Belmonts. Also Juste and Leon are far less muscular than Simon so that also brings problems.
So my choices for the 4 alts would be:
-Simon, the Defeault.
-Trevor: i know what i said about the coats, but Trevor is just too important to leave out. He was the first Belmont to beat Dracula, he appeared in other CV games as a legacy character, and is in general the 3rd most recognizable Belmont alongside Simon and Richter. I don't think Smash would even use the Netflix series design as adaptations like those are pretty much ignored in Smash (except for the likes of Advent Children, which in that case was a direct sequel to FF7 in Film form, as opposed to Netflix was just a licensed CV cartoon) and in general the old designs of Trevor of CV3 are rarely used unlike Simon, so the Curse of Darkness look will probably be used here, as that is the most common design used for Trevor, even in his Smash Spirit, so i think they would go for that.
-Christopher: The most underrated Belmont. He was originally supposed to be the one that first beat Dracula (as implied in the CV1 instruction manual in Japan, but due to developer miscommunications between CV3 and the Adventure, they both ended up beign different games, with Trevor (known as Ralph C. Belmondo in Japan) beign the first, and Chris beign second. Still, he was the first Belmont to ever beat Dracula twice, and the first CV character to do so. Plus his design is similar enough to Simon, so i think he would make for a great Alt.
-Richter.
Like how Simon uses some moves from Richter and vise versa, it would be cool if they also inherited the other Belmonts powers and vice versa, Like Trevor's Kicking attacks for an infinite Jab, or Christopher Belmont's Fire Projectile for a Side Smash. But despite this possible ideas, im not intersted in the idea of Simon beign turned into "Belmont". Simon is good enough as is, and represents the CV series wonderfully, with Richter as an extra fanservice, and the only changes i would do is make them play a little differently (IE: Remove Richter's moves from Simon and give him new moves)