The second question deserves its own thread as they’re different topics altogether.
That said, the first one - There’s no pattern or formula or patches wouldn’t exist.
The only way to “balance” an imbalanced game is to put it out there, have people critique what happens and fix those issues.
For example: Let’s make up a fighting game, so I’m not pointing out any bad games here that could potentially start a war.
Let’s call this game “Sidewalk Fighter 2 Turbo” and it has 16 characters.
The game gets released and the players have at it.
A week after launch, a popular venue has the first “tournament” in the game, and the character “Ren” wins top 7/8 spots.
Is that game suffering from imbalance? No, not yet. Why? It was out for a week.
Fixing this would be a mistake, as we saw with a certain “OP” character in a certain crossover game that came out February 2011, when the real problem was another character that wasn’t nerfed at all.
Two weeks later, Ren has 1 spot of the top 8. Now, Bunly has 4/8 spots, and 3 other characters fill up the rest. The game is looking pretty balanced, yes? Keep in mind, this is still 5/16 characters.
Over the course of the next few months, Bunly is becoming more and more dominant. This character is seemingly causing a great imbalance. Another thing that was noticed is that John has never even seen top 16.
NOW, it’s up to the designers to analyze these matches. Why does Bunly have such a dominance and John has so many shortcomings?
So they realize that Bunly is a fucking wall that can hit confirm off of a stupid high-priority move and take half of your life that has a guaranteed follow up 50/50 situation where you could lose the rest of it. They should then decide to reduce the hitstun on that high priority move and remove some of the “wall” type moves. Then John loses to jump-ins because there’s no good anti air, and he can’t capitalize on a hit due to lack of variety in moves or poor hitstun, and even when he can capitalize, his damage output is horrendous. They should then decide to perhaps give him some better damage and more hitstun on certain moves. Perhaps buff his seemingly useless anti-air so he has a better option, as most jump-ins don’t come straight down, and they come on an angle.
Now, if they went ahead in the week 1 tournament and nerfed “Ren” when they didn’t need to, they’d make the character useless.
That’s how the games are balanced. You analyze what people are saying and showing being overpowered and underpowered and fix those things. Some people think it’s as simple as nerfing health or making some moves completely useless, but typically they have to be much more specific than this. An example of this is Akuma in Super Turbo. No character has a single answer for his air fireball, making that move alone what makes him broken. He’d be top tier for sure without, but not broken. They can decide to take the move out, reduce it’s power (perhaps if it only went half screen), or cause him to have a huge amount of recovery when he lands from the jump OR take the opposite direction and give every character something that they can use against it.