Around since the original game is a moot point, as Impa never actually
appeared in a game until Ocarina of Time. Just in the manuals for Zelda 1 and 2. And even then, she doesn't do anything except tell Link he needs to go save Zelda. I guess that one Toad that told Mario and Luigi Peach was in trouble in Mario & Luigi Superstar Saga impacted that game's story.
Aside from that, she barely influenced the story in the games she makes an actual appearance outside of Skyward Sword. I'll give her credit for that game.
Ocarina of Time is second best; she
did hide Young Zelda away and was the one that came up with the Sheik idea. And serves as the Sage of Darkness.
The Oracles? Barely appears in Seasons and holds no major plot importance, and in Ages, there's only a small part where she's possessed by Veran to trick Link into leading her to Naryu.
Link Between Worlds? Just one of the Sages Yuga turns into a painting and nothing more.
You have counted wrong.
Impa:
Ocarina of Time
Oracle of Seasons/Oracle of Ages (Much like the different Pokémon versions, these games are counted together)
Skyward Sword
Link Between Worlds
And a cameo as a glass painting in Wind Waker in the prologue. Again, she doesn't actually appear in the first two Zelda games.
Epona:
Ocarina of Time
Majora's Mask
Four Swords Adventures
Minish Cap
Twilight Princess
And like Impa, a cameo in Wind Waker in the prologue. As well as a cameo in the Oracle games' openings.
Literally....irrelevant to the point.
Point being that Dark/Shadow Link is more recurring and more significant to the franchise as a whole than Impa, which cannot be denied.
Being a dark copy of Link does not render this invalid.
Hate to break it to you, but Impa is
less important that you attempt to give credit for. The "facts" you say cannot be argued are not factual.
So you're saying that Impa is more important than
Zelda, and claiming that anyone who argues otherwise is in denial. Ironic.
You see, this is the problem with the mindset of the "Impa should replace Sheik" crowd; they seem to forget that Sheik
doesn't actually exist as an individual character. Sheik is Zelda in the same exact vein as "Zero Suit Samus" is Samus and Ganondorf is Ganon; they are alternate identities for the same individual. Yeah "Sheikah Zelda" was only used once, but it's still Zelda and should be evaluated as such rather than at the individual level.
The opposite is true. It seems that the Impa fans
really have to stretch that she's even
close to the main 3's level to the point they delude themselves and attempt to justify their delusion.
In prominence, she falls behind Tingle, Epona, and Dark Link. It's debatable whether Vaati is also ahead of her considering she has more appearances yet
all of Vaati's have been major in comparison.
We had less semi-clone newcomers in Brawl than clone newcomers in Melee. With only one of them not being meant as "if there's time" filler
. Unless you're referring to the cut newcomers as well, which would bring it up to one less than Melee unless you count Toon Zelda/Toon Sheik separately.
As for how "called for" they were, other than the cut Toon Zelda/Sheik (one Toon is enough) I'd say they were all called for.
And no, if Sakurai was capable of replacing Young Link and axing out Pichu entirely with no replacement in line, he was capable of kicking Sheik out. Laziness is a horrible excuse.
Or, and bear with me on this, they work on what makes the
Zelda half of the combo bad and not take the Sheik half away. People seem to have trouble grasping that taking Sheik out isn't going to magically make Zelda better.
And while Bamco is here to help with balance, Sakurai does get final say on any changes made. They tell him to toss out the transform gimmick, and "*laugh*".
There are some differences, but all in all, some things are just the same.
One of which being that Sakurai wants to include as much of the old cast as possible and hates having to make cuts. If for some reason, Sakurai
has to cut Sheik, it won't be to make room for Impa.