Is it possible or necessary to level the playing field in fighting games between skilled and not skilled players?
Nope to both.
The only way you can level the playing field is by making skill less influential on the outcome of the game. You can do this either by reducing how difficult the optimal outcome is to produce, or by reducing the amount of advantage conferred by the optimal outcome relative to the least optimal outcome. Or you can do this by having randomness be a much stronger determiner of who actually wins the game.
Of course, all of these things will piss off skilled players. You might have some limited measure of success depending on the implementation though. I’ve been arguing that randomized bullet spread has been bad for years and should be replaced with damage dropoff relative to distance to get the same effect and I don’t think anyone agrees with me on that.
Since the difference between skilled outcomes and random outcomes are difficult to distinguish, especially when the two are combined, randomness seems to help some games out, like Hearthstone, Call of Duty (Red Orchestra devs once called CoD out for this), maybe SF2 (never been explicitly called out for this, but it is the most mainstream popular SF game, so it’s possible the randomized damage and stun had a role), and Smash Bros with items on. Randomness mixed with skill tests allows weaker players to feel good about their skills when they occasionally win, possibly adding to the overall “stickiness” of the game for a wide audience, while still allowing players to build consistency overall.
However Luck can still be beneficial from a business perspective. This talk by one of the famous designers of Magic: The Gathering basically makes the argument, “Luck is really good at attracting players, introducing more luck into a game angers existing players, so you should start out with as much luck as you think the game needs, then reduce it over time as the playerbase matures.” And it presents the case of Team Fortress 2, which followed his pattern of high luck early on and reducing it as the game grew older, which was pretty successful for TF2.
Smash Bros Melee had a natural release valve in this way. The default modes and stages have items and other random effects, but the game offers options to turn these off, so as the game matured into its competitive format, players had the ability to turn off most of the randomness and get serious.
So to build a successful game, randomness helps to attract an audience, but it should probably have patches to reduce the effect of the random elements over time, options to mitigate the randomness that are made low-affordance on purpose so the community can slowly discover how to mitigate or remove randomness, or variant rules to remove the random elements.