So I got myself thinking again. I tried making a point the other day that recency or whatever matters quite a bit. I'd like to redact and rephrase my argument.
What I believe NOW, is that for particular series and or characters, there are exceptions or a clause of sorts.
For example, Mario, Zelda, Donkey Kong, etc...for the most part don't have a cast that changes on a regular basis as far as the main characters. For this reason, it is highly likely that no Mario, Zelda, or Donkey Kong character currently on the roster will EVER be shaved off, unless there was a reboot of the series. This would basically apply to Wario Ware, Yoshi, Metroid for the most part.
There would most likely not be any sort of addition based off of recency, because the main core of characters, the necessities, are always going to be there. Ridley, I personally believe is the only character that would be justifiable for Metroid. Otherwise, Metroid shouldn't get a character because very few others are as important or reoccurring as Ridley, whether his size is a problem or not. K.Rool is a wee bit different in my opinion. While I ( and basically everyone else) will always view him as THE Donkey Kong villain, he currently is not a focus of DKCR. Whether that will be a problem for him is yet to be seen.
Star Fox is questionable at best. I believe the most recent game for Brawl at the time was either Assault or Command. For Star Fox, the basic cast is more times than not there. Falco is a staple. Wolf is a staple. While Peppy and Slippy are staples, it would seem that they aren't incredibly likely. I just personally don't see them being clear and cut fighters like the other three already are. Krystal COULD get in, but i'd rather those three stay will differentiated movesets than get rid of 3 important characters that have been there from the start and could be different in the first place. Based on the fact that Bowser is now a beastly looking character, I wouldn't doubt Falco getting fixed to be more unique. I fully expect at least one of Falco or Wolf, while i'm not counting the other out either.
On to what I mean by exceptions or clauses. I am referring to series that either do not have a sufficient amount of characters, are added for particular value, or have changing casts. This refers to any retro additions (Ice Climbers, Pit (arguable because of KI:U)), WTF additions (G&W, R.O.B, Wii Fit Trainer), or series with spotlight characters like Fire Emblem or Pokemon.
Classic or retro characters are basically added for a valuable look at the past of Nintendo. Ice Climbers fit this perfectly. It is highly (AND I MEAN HIGHLY. WE AIN'T GETTING NO CONDOR) unlikely that we will be getting a second Ice Climbers rep. Ever. Unless they revive it like Kid Icarus, and we get a solid supporting character. However it's arguable that the series wouldn't need anything else other than Nana and Popo, which is a scenario that could be applicable to Kid Icarus and Pit.
Anyway, onto the WTF characters. These characters are added for shock, as they are completely unexpected and rarely requested. It is entirely possible that Wii Fit Trainer isn't the WTF character, but I'd say it's likely. G&W and R.O.B are unexpected, but reflect back on major parts of Nintendo history, and work well as fighters to boot.
Now onto series with changing casts. Pokemon and Fire Emblem are essentially the two major series that get affected by this. First, we'll cover Pokemon. Pokemon, while flooded with Gen 1 characters, has had characters from newer generations represented, Pichu and Lucario are the examples. With this in mind, it is highly likely that we get a newcomer that is fresh and new. While Mewtwo is a Gen 1 character, he (she?) is refreshed in what is now Gen 6. However, several others are getting the treatment as well. This includes Blaziken, Absol, Mawile, Ampharos, Lucario, etc... Compared to the others, Mewtwo has been given the most exposure to fans, so it is highly likely that because of popularity and current role in Pokemon, Mewtwo will make a return, and I almost want to say that Lucario will not be lowest on the totem pole. Remember, Jigglypuff was last in priority for Brawl, and Ness was almost removed. So at this point, while Sakurai doesn't like cuts, it's entirely possible for an Original 12 to be cut. It's fairly obvious that the only character of the original 12 that could be a justifiable cut is indeed Jigglypuff, who now plays hardly a role at all in Pokemon besides being in the wild.
Fire Emblem is in a similar boat. Because the cast changes from game to game, it only makes sense to add a character from the newest installment. It's not that i'm saying to add the newest lord just because, i'm saying it because it just makes sense. It's entirely logical to add Chrom over Roy, whether the latter had data on Brawl or not. At the current moment, in the grand scheme of things, it just makes sense to add Chrom. This is because, like Pokemon, the cast is always changing, there are always new characters in the spotlight, and I wouldn't doubt that there are reasons for having characters in the spotlight. I know some believe that characters other than Chrom will get in before him, but I just can't agree. We have yet to see a character other than the frontrunner, main protagonist get in. Having Lucina or Owain, or somebody get in over him would be like putting Wonder Blue in without Wonder Red. It just would make no sense whatsoever. That isn't to say that Lucina or somebody else (but probably Lucina) couldn't get in along WITH Chrom is outside the realm of possibility, but I'd say it's unlikely. Roy is at a major disadvantage in this regard.
I think this is a very decent way in looking at the roster. I'd get into more about newcomers, and I may later, but i'm sick of typing for now.