The term in this sense means characters who "come with the main character but aren't needed".
Of all my favorite video game characters, Sonic is the one I link most to happy memories and some of the worst ones too. I can remember at the Family Centre (before the council closed it down) waiting FOREVER for 5 mins of gameplay on Sonic 2 and was bummed by the notion I couldn't play Sonic 3 and Knuckles when they both came out. And for a long time I would watch with glee as new games came out and even newer characters enriched the Sonic universe. In the last few years I've come across the term of such characters being referred to as "tagalongs", being unneeded for the series.
Whoa. Whoa. Whoa...
Okay so if we take away the other characters since Tails' introduction (which I believe is what a guy from IGN said), theres... 1... or 2... Games??? 2 games where Sonic didn't have them in. Even unleashed needed Tails at the very least for its plot to hold together. And without the other characters, Sonic doesn't appeal to his fans, even Silver has his fair share of fans despite being linked to half of Sonic '06's problems.
Which brings me round to the main point of this article, when AREN'T characters needed? When I think of this I go over in my head of series where characters were introduced that weren't needed. There are basically NONE. Side characters are there to slot into the storyline where and when needed, be it for humor reasons, be it for plot reasons or another reasons.
And tell Mr. Oda the mangaka of One Piece he doesn't need half his cast, if there's one thing Mr. Oda knows, its how to use a side character. Just when you thought Crocodile's fate was sealed for good, Oda brings him back to be nothing short of "bad ass" as some have put it.
In fact there is only one scenario I can thing up, particularly in gaming, when you don't need other characters at all; Fighting games. Mortal Kombat is first to pop into my head. There are MANY characters, only 60+ I recall from memory, most are just rehashes of older characters. All characters are written with the basis in fighting character that in the next game they could be replaced with a similar character who is a more "up to date" version of the older one. Mortal Kombat tried this with Shinjinko and Liu Kang. The fans hated Shinjinko, despite being "the next generation Liu Kang".
Now fighting games only need their core characters, when I think of MK I think of the cores being: Liu Kang, Raiden, Kitana, Scorpion, Sub-Zero, Sonya, Jax, Kano, Baraka, Shoa Kahn, Kung Loa, Johnny Cage, Tshang Tshung (whose name I can't spell) and Reptile. Everyone else is extras, with their own fair share of fans. But there characters you can have together in any game and it will hold itself together pretty well, MK Vs. DC left only a few of these guys out and it held itself together as both a cross over and an MK game. So why does MK need the other 40+ characters? Well this is heading in one direction:
Back to Sonic - its a case of having the right character there for any scenario. You want someone who can fit the role of hard nut and comic relief, you've got Knuckles. You want a character who can look bad ass no matter what you have to have him do in the plot, you've got Shadow. You want someone whose morally torn between right and wrong, you've got Silver. It goes on.
And finally, when one character comes along that changes a series, thats when you KNOW these so called tagalong characters are doing their job. Sonic was a very kiddie game until Shadow and Rouge showed up. Whereas Mario always remained kiddie friendly. In fact I'd like to end this on Mario.
Mario is VERY popular. But you know, unlike 90% of the games out there, while he has done many games and many different things, Mario himself hasn't REALLY done anything anything to move himself forward as a game series. Nintendo tends to save that for the games like Mario Galaxy, which is nice overall, except those gameplay styles don't ever make it into the main game itself. You can pick up any Paper Mario game and know what it is going to do for you. You can pick up any mainstream Mario game and know how it will play. The many games for Mario are so separate, the character gets new games all the time but never progresses overall as a series forward, it just gets a bit better looking.
And there are many characters within the Mario series who are so indifferent, theres about 3 or 4 versions of any character with a similar or almost identical role. There Wario... Theres Mario... But Mario often plays the same as Luigi... And Vice Versa... Aside from Luigi's a coward and Mario's brave, their the same character! Shadow can't get away with playing Sonic's role they do similar things but their very different characters. Tails can't play Knuckles' role for the same reasons. Amy can't even get away with Rogue's role because sassy and cute are too different things. So why does one series whose characters are more 3D get told to drop those rich characters and another series whose characters are more 2D get away with it?
So is there really such a thing as "tagalongs"? No not in the sense that IGN and the others think. But IGN hates Sonic, so in my opinion their views are nothing short of being biased. But you know, they've got the attention of half the gamers out there, they can say what they want and get away with it. Side characters are there to move a series along, and that's why no series can sustain itself without them. The only thing is overusing them can be bad or putting the wrong character in the role suitable only for another. And by the time the game comes out, its already too late - that character has fans even small amounts.
IGN should read some One Piece sometime... Haha, that is if they can survive past character 50.