If I had to pick I’d have to say the philosophy that I most agree with is the one used for competitive pokemon. There’s actually a couple things in competitive pokemon that can land a pokemon in the Uber category (which for the comparison is the same as being banned). When a pokemon is used very frequently and appears on almost every team, red flags are definitely thrown up. The same is true of fighting game characters. High usage, especially in tournaments, leads to some suspicion. However this alone is no basis for a ban, simply a likely indicator.
At this point you have to figure out if the character fits into one of two categories. The first category is the “unfair” category. Generally, characters don’t fall into this category. Going back to the pokemon example, a pokemon that was banned for this reason was Wobbuffett. Wobbuffett is a guaranteed kill, and a high possibility for a double kill. The equivalent to that in a fighting game would be a character that had an unblockable, unavoidable, invincible, instant kill move that could be performed regardless of any gauge or resource. In other words, a guaranteed kill. As far as I know, there’s no fighting game with such a character.
The second, more common reason for a ban is limited counter measures. Once again pulling the pokemon analogy, the likes of Mewtwo and some other legendaries are banned for this reason. There are only a handfull of pokemon that can stat-wise compete with such pokemon (and most of those pokemon are the legendaries themselves), and therefore when making a team you either include such counter measures or resign yourself to lose against such pokemon. The equivalent of this in a fighter would be a character that cannot be successfully defeated, regardless of player skill, unless certain “counter-measure” characters are picked. Characters like this do exist, but are few and far between.
In short, there’s not many situations in which a character should be banned.
~Arch Angel~