A lot to unpack. Played the game on my own, so please let me know if you think my critique would be affected by another player.
I should start by saying I love the differences in the two characters, with one being primarily close-range and another being primarily long-range. However, at the beginning of each game, both players have to get close in order to accomplish anything, which I can imagine would lead to each game starting with one short, close-range engagement before the ranged player backs off and tries to use their abilities. Once they're out of power, they can't do anything at all, so they have to bring themselves back inside the close-range player's attack range, who from what I can imagine (again, please let me know if you think differently) would always win the engagement trade, as they have abilities focused around close-range as well as a spammable mouse-click attack.
I love the effort to balance each character's movement options, I believe they're almost implemented on the wrong characters. While it makes sense for the long-range fighter to be able to float and for the close-range one to use a grappling hook (which was immensely fun to play around with by the way, it feels great to use), it leads to another problem with the balance. The close range fighter has a very, very easy escape option with the grappling hook, which is something I feel is more needed on the ranged character, as they needed a faster way to get back to a good attacking range for them in my opinion.
However, while most of my critique has been about the balancing with the close-range character, the long-range one also has a few problems. While the "power" system was implemented well, some of the abilities are a little overpowered. The long-range character's fireball attack is from what I can gather (having tested it from opposite ends of the stage) completely unavoidable. As well as this, the close-range character's shuriken storm attack is almost unreactable.
Another thing to add is with the stage selection. Each stage is identical functionally, which while isn't an issue in itself, sometimes the stage's hazard doesn't work. Every third game would see the hazard at the bottom of the stage fail to be spawned. As well as this, it also doesn't stretch to the end of the screen, though I should add that the collision still hits both of the players if they're in the area that isn't covered, so it still functions correctly.
The last thing to mention is the controls and menu. The main issue I find with the controls is that there's a lot to remember for each player, and it can only be shown at the main menu. This problem could be solved by creating a pause menu, with an option to view the controls again on there. As well as this, there is no option to exit the game from within the game itself. This could also be added to the pause menu.
Overall, I still had fun playing your game, and if I have the time to go back through it with a friend, I will.