Ok I hate to be the guy whos's like "Um akshully it's quite simple
", but wouldn't estimating how much effort it takes to make a smash character actually be kinda easy? Like, it's not witchcraft, theres plenty of information on general game development.
Every character has a 3d model. There's tons of 3d modelers out there, i dont think it would be that difficult to find information online on how much time it would take to model a character at a given level of complexity.
You can just count how many seconds of animation a character has. I remember hearing somewhere that a professional animator can make 6 seconds of animation a day, but I cant remember if that was for a single character or a whole scene.
You do have to program the characters, but they have to have that down to a science by now after making 80 of them. Programming characters has to be more like filling out a spreadsheet, i just have a hard time believing they regularly run into novel programming roadblocks. Even steve sounds like he was more
tedious to program than actually difficult.
Designing them probably is the hardest to estimate since it's purely creative and we wouldnt entirely know the kinds of things sakurai has to consider. I think the only time he gave an answer to how long it take to design a character is when he said he came up with greninja's moveset in a day. So it probably takes at most a couple weeks.
Then you have to add the beurocrasy- approving the animations, approving the models, approving the sound effects, getting approval from the licenses, so on and so forth. Gonna be real this is probably like half of development time.