Not really. While there is no concrete definition of what a Mary Sue is, I don't think that's what they were thinking of. Yellow's Mary Sueness comes from more of how "special" she is.
I do believe she acts more like a real person her age than the rest of the cast, and I don't think being interesting is a good reason to call someone a Mary Sue.
I believe that was just what she decided to do, not because her abilities forced her. See Wataru, he has the same ability yet is fine with battling. Plus, Yellow is fully capable of battling (as shown throughout Yellow and in FRLG), she just chooses not to because she doesn't like it. Her empathy is mostly used for the plot rather than her character anyways. Heck, FRLG made it so her powers can raise her pokemon levels. That doesn't help her character flaws whatsoever.
Actually, Yellow raised the levels of her Pokemon during the battle against Lance, that wasn't just a FRLG thing, and because she doesn't like battling she obviously doesn't train her Pokemon, so how else can she gain levels? I don't know what extent she can do it FRLG, but I know in Yellow it was just to make a more interesting climax.
I agree that her innocence isn't good for secret missions, but... there aren't really any secret missions. And Yellow gets involved in the danger anyways; her childlike innocence is used to be her more "likable" for us and the other characters. And that shows; for everyone that has talked to her, most like her and care for her. So it really isn't a flaw and being liked by everyone that isn't "evil/mean" can be a trait of a Mary Sue.
Um, have you read Yellow saga? Green (JP Blue) gave her a secret mission and she went under the alias "Armillo del Bosque Verde" as a boy, but Lorelei saw through it.
May I ask what battle? The only time I remember of she falling asleep is in FRLG after being useful for the plot.
Again, Yellow Saga:
-> In the battle with Lorelei with Bill, she fell asleep after moving the Pokeball on the rod, if I recall correctly.
-> After fighting with Lance she fell out of the sky to be caught by Red and to wake up later.
She isn't useless for the plot, but is quite boring as a character. We know she'll conquer each time and will have people/pokemon behind her. There is nothing interesting about her enough to like her and her powers are more interestingly used by Wataru (or would be if actually had more manga time). Yellow doesn't really have a unique personality (maybe unique in a world where most people battle, yeah) as much as the typical carefree, caring female character.
Who is Wataru? Oh, Lance. I think they are both pretty interesting. really.
Anyway, I don't know what FRLG made her, but she seemed much more dynamic in RGBYGSC, she was tomboyish yet sensitive, mysterious yet open, funny yet can get serious, she was childish yet mature, her dynamics with characters are interesting, and I think she is awesome. She is an original character that doesn't adhere to a video-game archetype like, "Player Character Idiot Hero That Wisens Up" "Rival With Attitude" "Distaff Counterpart to Player Character", and I think because she is an OC, she is disliked.
But I respect your opinions, I might be a bit biased. The very first Pokemon anything I ever had was Volume Four of Pokemon Adventures (Special). I remember, seeing some old lady find some sort of mysterious thing and wondering "Oooh what willhappen", I remember some sort of kid that seemed to be doing well with these interesting Pokemon and I thought he was going to be the hero but *bam* he gets kidnapped or something, and then there was this poor injured Pikachu and this one suspiciously girly boy coming along, doing mysterious stuff and amazing the tough-to-impress professor, carries on the mantle of the previous hero in an interesting quest to find him, she eventually winds up using an interesting plan to defeat Lorelei and the 'Nerd, not only did she use these awesome "Pokemon" guys and psychic powers, she uses her mind and thinks sharply. By the end, we get to know this rival guy and it just left me with so many questions and it was so interesting, I loved the character Yellow and the Pokemon's designs so much that I had to read more.
Realistic as in completely boring? Saving each other all the time is overused, overdone and shouldn't be used solely for attraction. It's like watching grass grow, you just want something to happen.
Um, stuff *does* happen. I mean, you can't get any more overt in terms of romantic attraction when your Pokemon make an egg. I mean...you can't really get any more overt than that in Pokemon media.
Aside from that, it went from Yellow seeing Red as a Mentor, than a friend, than maybe something more. It bloomed all the time in RGBYGSC, again, can't speak for FRLG.
I see Yellow as a plot device. Is there any arc, or heck scene other than her just talking where isn't used for plot device?
I think you are confusing "plot device" with "character who is an actor as opposed to re-actor in the plot".