Please note what I've italicized. The following list will order character based on how NINTENDO values their characters currently. A character may have been important to Nintendo before, but trust me, those things change, and Nintendo's actions reflect that.
Character Importance to Nintendo at the present time:
S - Valued Highly
A - Valued
B - Valued Slightly
C - Not Valued
D - Milked Dry
E - Unimportant
F - Forgotten
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Mario - S
Link - S
Pikachu - S
Samus - S
--
Pokemon Trainer - A
Wario - A
Luigi - A
Peach - A
Kirby - A
Bowser - A
Ganondorf - A
Zelda - A
Marth - A
Olimar - A
--
Yoshi - B
Sonic - B
Toon Link - B
Lucario - B
Donkey Kong - B
Metaknight - B
Diddy Kong - B
King DeDeDe - B
R.O.B. - B
--
Zero Suit Samus - C
Captain Falcon - C
Sheik - C
Fox - C
Pit - C
Ike - C
--
Jigglypuff - D
Mr. Game and Watch - D
Ice Climbers - D
--
Wolf - E
Falco - E
Snake - E
--
Ness - F
Lucas - F
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WHAT?! That list is stupid!!! Original 8/12 are OBVIOUSLY the most important! You don't know what you're talking about!
No, I addressed what matters. A character's importance to Nintendo right now. Not Sakurai's value of importance. Not how big of a fanbase cult following they have. Not how important to Nintendo they used to be. How much Nintendo cares about such a character right now is what I've shown.
But...but Ness & Lucas aren't forgotten!!! Sure they are. Nintendo won't be trying to do anything with them. Lucas isn't even going to be brought to the US by Nintendo. Sure, you've got the cult fanbases making the translations for you. Doesn't matter. Ness and Lucas are done. Sakurai might like them and feel the need to plug them in, but Sakurai doesn't represent Nintendo at all. If Sakurai had cut Ness and didn't even bother to add Lucas, do you really think Nintendo would have stepped in? No, they wouldn't. Ness and Lucas are non-existant to them, they don't plan on getting any more money from those two characters.
Fine! But you've obviously biased against Star Fox! Funny, that I'm biased against one of my favourite series, I guess that explains why I put Pikachu in D rank. Oh wait, no I didn't. This is hardly bias, this is reality. Star Fox might as well be 3rd Party to Nintendo at this point. Sure they used to be valued but Nintendo doesn't want to waste the time or resources making a Star Fox game anymore, so they continually place someone else in charge of the game, such as Namco for Star Fox: Assualt. Fox is not valued by Nintendo, it's silly to think such a thing. If a Star Fox game never appears, Nintendo wouldn't really care, they don't really care. If someone else is willing to make a Star Fox game for them, they'd be fine with that, but they aren't going to going out of their way for Star Fox, it's become increasingly more obvious that the series is no longer a tier giant such as Mario, Metroid, or Zelda. Falco and Wolf are laughable, Nintendo could care less if whoever makes the next Star Fox puts either of those characters in. Write them out some clever way and Nintendo wouldn't mind.
Sonic!?!? He's not even a Nintendo character!!! How could Nintendo find him important?? Nintendo, Sony, and Microsoft are all aware of the importance of Sonic. He gets them money, and plenty of it. If the Sega Team has an idea for a Sonic game, no one is going to want to pass it up. That's a terrible move, Sonic sells. Nintendo values Sonic for the money he gets them. In fact, they value him more than Sony and Microsoft due thanks to the 'rivalry' that was established between him and Mario. They can milk that better than Sony and Microsoft can, allowing them to obtain 3rd party exclusives such as the Olympic Games. Sonic is obviously valued by Nintendo, easily more than those below him, don't lie to yourselves by saying that since he isn't a Nintendo character that Nintendo doesn't value him.
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I'm not finished, I'll write out more later. But trust me, the list is very accurate. I hate to say it, but if you have a major disagreement, you're probably wrong. If you have a small disagreement, the difference is probably pretty subtle. But please try to think in the same mindset when trying to point something out. I don't care about Sakurai's opinions, he isn't Nintendo. I don't care about the opinions of the fans, it's silly to judge those when it's much better to judge Nintendo's response to them.