See, I'm all for "X character should get in for these reasons", but a lot of what I see is stuff nobody cares about at the end of the day. In Smash speculation, a LOT of people forget that this is still a fighting game. On one hand, it's a party game where friends come together to play. On another hand, it's a highly competitive game where the skills of several players are put to the test. What truly matters in this series is the gameplay, end of story.
I can argue that Inklings should get in because they're new. But nobody cares. They want to know what they can do. How can they use their in-game skills in Smash Bros? Adversely, Jumpman (who I believe is simply Mario. End of story for me), and the ideas presented seems like forcing a character into the game for no reason. Sure, Donkey Kong Arcade is important to Vidya history; nobody is denying that. However, when I'm playing Smash Bros., I want somebody who is fun. I want somebody who is different. To me, "Jumpman" being a separate character seems like it's simply used to "represent" one game. That's a waste. Especially when we have Mario, Donkey Kong, 75m, the hammer item...not every game needs to be represented by a character. I can understand the passion for wanting a character. But regardless of how important Donkey Kong Arcade is, it doesn't need its own character when it technically already has the protagonist and antagonist, a stage, and item from it.
Onto Inklings. They're perfect. Pretty much everything about them is awesome. I've posted ideas for them in the past. I view them as a spacing/stage control character, shooting ink all over the stage which can damage opponents, or if characters run over it, it makes them slip.
Because of the different classes in Splatoon, the different weapons can be different custom moves, and change the way the character must be played. Using assault class weapons can work better for overwhelming the opponent, whereas a sniper ink gun can be used for spacing/projectile attacks. Rocket Ink guns can be stronger but slower, and promote a risk reward type play. However, the core gameplay with the rest of the moveset remains the same; so a spacing/stage control moveset at its core. But the special attacks can be altered for different strategies.