My concern with those genres is elements conflict. I'm afraid you'd ended up with game which only have a few elements of each genre or one genre overpower the others. I don't know about others but IMO combining genres requires main element of each genre to stand out or be significant in gameplay.
I'm not sure how you'd combine Fighting with Parkour since each has its own focus.
Also IMO just because a game has boss fight doesn't mean it is Fighting game.
that's quite the concern i have at the moment, in all of this comes in the end is execution. how well would you blend a runner game that you have only a few movement options to boost yourself further as well fighting against enemies.
boss fights dont count for the "fighting" aspect obviously.
the gameplay should share the basic concepts of each genre and in later additions/updates it expands the movement and combos.
fighting games have a main gameplay standout and that's you're fighting against another player (or ai) and having lots of flexibilty to use your combos of your character. many games dont have the flexibilty to create your own combos and it lands dull.
parkour elements are mainly inspired from mirror's edge, while tough to pull off if done correctly this would be a good addition.
the score system is also something that shouldnt be underestimated as it'll decide your rank.
all of this needs to be done in a way it's simple in controls but difficult to master the combos and adding more points.
