Basic Trope: Between two releases of a game, an overpowered character / item / dynamic is tweaked to make it less gamebreaking.
Straight: In Generic Fighting Game, Bob is a very powerful character who is very adaptable to a very specific, unbeatable strategy. In Generic Fighting Game 2: The Revenge Of The Sequel, he's been tweaked to be merely a very strong character.
Exaggerated: Bob is the definition of Game Breaker, where even the flimsiest button masher can play as him and beat any skilled player using another character. In the sequel, he's a full-blown Joke Character.
Downplayed: Bob has That One Attack in the first game, but is otherwise just a good all rounder. In the second game, either he's been weakened a little on all other stats, or That One Attack was made a little weaker, so he is now a fair character.
The creators of the fighting game want everyone to have a fair shot at winning with any character, so the tweak was necessary.
Alternately, a storyline explanation for Bob's relative loss of power is provided.
Inverted: Bob was pretty useless in the first game, but the second game adds a mechanic that allows him to be a much more effective character.
Subverted: It seems that nothing has changed between games and Bob still reigns supreme.
Double Subverted: Until the sequel releases patch 2.0, designed to fix that exact problem.
In the sequel, Bob is initially considered worse than the resident Joke Character, Joe Blow...that is until Tourney Players later find out that his taunt-canceling provide for a brutal metagame strategy causing others to fear Bob once more.
Alternately, the game designers knew the Fan Dumb would rage against the loss of their favorite Game Breaker. So, they lampshaded it by equipping Bob with weapons made out of NERF foam.
Zig Zagged: The sequel doesn't change too much...until patch 2.0. But there's still a way around it if you look...
Averted: Bob didn't get nerfed.
Enforced: "These online players are whining that everyone plays as Bob. Tell those programmers to get off their duffs and start fixing this!"
Lampshaded: One of the character telling that Bob is stronger at first, but he's now weaker.
Invoked: "Remember, the testers found that Bob was too overpowered. You need to fix that."
Exploited: A player of Generic Fighting Game learns in advance of the changes to Bob, and uses this to dominate in several matches before the rest of the players catch on.
A programmer, curious as to how intelligent the players are, doesn't balance the characters.
Or, instead of nerfing that particular character, the other characters are given boosts and counter-measures to deal with it.
Discussed: "It seems like everyone who plays this game online chose Bob...until the sequel came out."
Conversed: "Man, I can remember when Bob was super-powerful. Now it's just not fun."
Deconstructed: Fans of the game - and of Bob - start massive protests because they feel that the usage of a Game Breaker is legitimate play. The sequel tanks for this reason.
The fans start playing the sequel and find that Charlie is a pretty good character to use...
Other fans rejoice at the fall of Bob because they thought he ruined the first game. The sequel does just as well as the first because it pleases as many people as it pisses off.
Hurry back to Nerf before they change the page to make it less awesome... Yet again!