This topic is intrinsically linked to a discussion on game balance. That is to say, the answer to the original question depends on the answer to whether or not the game is “balanced.”
Case in point:
In fighting games, I would say that THE criterion that determines whether or not a player feels that a game is well-balanced, is whether or not that player feels that this (the above statement) is reasonably possible. We “know” this intuitively; it is the genesis of (our understanding of) the concept for us.
[details=Spoiler]Casually:
If you pick a/the character that best suits your likes/dislikes/sensibilities, and you understand at least the basics of the character and you try your very best to win with them, and you still think you have a better shot at winning if you pick another character, you will interpret this as an imbalance.
Competitively:
If you pick a/the character that best suits your strengths and weaknesses and aptitudes, and you study and practice that character, and you still think you have a better shot at winning if you (learn and) use a different character, you will interpret this as an imbalance.[/details]
Of course this is a simplification. When I say “reasonably possible,” in this case, “possibility” is a sliding scale. We’re also probably only really considering/examining a handful of matchups out of an entire a game when we pass such a judgement. Everyone’s personal thresholds and sensitivities for balance will vary, too.
However, the idea remains intact. This is more of a working definition than a litmus test, but it’s real to you when you’ve personally identified an occurrence. In terms of your individual opinion, “you know it when you see it.”
When you find or run into a significant character imbalance, you are at a crossroads. You can…
- switch your main to a/the “stronger” character
- use or develop backup characters
- decide to play the counter-pick roulette
- accept that you’re voluntarily playing at a disadvantage, whether because of stubborn pride, or simply because of time already invested and experience already accumulated coupled with a shortage of time and/or will to “start over”; whether you derive enjoyment from this or soldier on stubbornly/stoically or are deeply saddened or embittered by this is actually immaterial to this discussion
- try to create/discover new (heretofore unknown) techniques and tactics that change the nature of the matchup(s) or game: “Maybe we missed something.”
- live in denial by attempting to lie to yourself (this means you’ve gone crazy)
- quit
Again, the route you choose to take with the game will/should depend on 1) how “balanced” it is, and 2) how serious you are about it.