I personally gravitate more towards the simpler-styled movesets also. I don't mind having some more complex characters and/or gimmicks, and in some cases they can make for some nice fun, but I'd like for them to make good sense for the character and not feel forced or shoehorned in.
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A simple dedicated tutorial mode and tutorial course for each character would go a long way in addressing concerns of approachability.
Sure, specialized tutorial modes for each character could potentially be helpful for players trying to transition from total newbie to a more intermediate level, and they could maybe even be implemented in a decently fun way if they were, say, turned into some sort of event-match type of thing, idk.
However, a lot of people just want to pick their favorite and jump into the fray with friends right away. There is a lot to be said from a game design perspective in terms of letting the gameplay teach itself instead of having to explicitly instruct players on successful strategies, especially in a casual-appeal party game like Smash. Smash specifically is designed in such a way that you
don't have to learn any special combos/strategies/techniques in order to start experimenting with a whole bunch of your favorites; this is one of its big successes design-wise. I gotta think they value the pick-up-and-play aspect; a lot of people (including me) get introduced to Smash in group settings alongside other people who have played the game before and would rather let you jump in with them rather than sit and watch you go through a tutorial.
With any kind of tutorial mode for Smash, I feel that you have to be clear that it is strictly optional lest you turn off droves of party- and playdate-goers who just want to pick up and play. And at that point you have to ask yourself how many people are really going to use it to its fullest: casuals might never touch it if it isn't required and therefore hidden in the menus, while most people dedicated enough to try to become intermediate/advanced players are simply going to look to online sources for strats and techniques.
The other issue I didn't even mention above is the potential resource drain, especially with the big roster that I think most everybody wants.
So, yeah, I think character-specific tutorials could make some nice side-content if they aren't too resource-intensive, but they're not a replacement for supplying an ample selection of newbie-friendly playable characters.