Tired of Lynn's poor sportsmanship during board games, the siblings decide to team up to take her down.
It's game night at the Loud House, and Lincoln explains to the viewers that he and his sisters dread this day, because Lynn always wins every game they play, and has the need to gloat about it in front of everyone's faces. When the siblings gather in the dining room, Lily suggests that they play Go Fish. As they play the game, Lynn manages to win, and begins showboating in front of everybody's faces, which is made worse when Lynn announces that this was her 300th win in a row. When Lynn shoots off some confetti (which is made up of the siblings' homework), the siblings declare that they're now sick and tired of Lynn constantly winning and/or gloating. Lincoln suggests that they play a game that Lynn has no experience in, since she'll most likely lose.
The first game they play is called "Pretty, Pretty Pageant Queen", which is suggested by Lola. Lynn is hesitant to play it, but decides to play it to avoid admitting loss. As they play the game, Lola appears to be winning, but just before Lola can declare victory, Lynn reads in the rule book that if you get 10s on all three dice at once, you get an instant win. Lynn grabs the dice, spits on them, and begins to shake them. Just when Lisa says that the chances of getting 10s on all three dice are highly unlikely, Lynn ends up winning, due to all three dice displaying 10s, causing Lola to faint.
Lana suggests "Plumbing Pro", a game that requires pulling items out without touching the sides. Lynn tries to grab one of the items, but she ends up touching the wall, shocking her. Because of this, Lynn has only one more chance, or else she'll lose. Lynn walks out of the house, and begin doing some exercises to boost her motivation. She runs back in, and successfully pulls out all of the items from the toilet, resulting in another victory.
Lincoln suggests that she play the Ace Savvy trivia game, since Lynn has no experience in Ace Savvy at all. However, when he and Lynn play the game, Lincoln has gotten every question wrong, because Lynn keeps making Lincoln lose his mojo by telling him that he might choke when he says an answer. When asked "Who is Ace Savvy's sidekick?", Lincoln buzzes in, knowing the answer. However, Lynn psyches him out by saying that it could be a trick question. Under stress, Lincoln answers "Massachusetts", and Lynn answers "One-Eyed Jack", once again giving Lynn the victory.
Just when the siblings start to admit that Lynn can't be stopped, Lisa suggests that they play a game that requires all of them to go against Lynn. Lisa presents the game she has in mind: "The Settlers of Cat-Land". The objective is to build as many structures as possible, which can only be done by forming alliances. If no one sides with Lynn, she's sure to lose. Later, the siblings and Lynn play the game, and the siblings end up being in first place, while Lynn ends in second. The siblings (sans Lynn) leave the dining area, and conclude that Lynn should finally stop with the competitiveness, and excessive gloating.
The next day, however, Lynn exhibits a more obnoxious side of her gloating, and is starting to become highly competitive, as she begins to chug a carton of milk faster than Lincoln, run up the stairs faster than Leni, build a taller wooden block structure than Lily, create an explosion with chemicals before Lisa (even though that wasn't Lisa's intention), wash dishes faster than Lucy, and brush her teeth faster than Lola. Not only does Lynn do this to just her siblings individually, but all of them at once, saying she can go to sleep faster than them, snore louder than them, and be the first to wake up. The siblings attempt to get away from Lynn by going on a peaceful drive, but unfortunately, Lynn chases after them on her bike, showing that she can go faster than them.
At night, the siblings hold a meeting, where they admit that beating Lynn at "The Settlers of Cat-Land" was a bad move. Lincoln suggests that they hold a rematch, but this time, they'll throw the game (meaning intentionally lose), so that Lynn will win, and hope it'll stop with the obnoxious gloating. Lynn accepts the rematch, and the siblings begin the game again. As they play, the siblings attempt to make Lynn win by giving her any card she requests, placing a valuable card in the card pile for her to pick up, and change the side of the die to a higher number. The plan appears to be working, when suddenly, Leni grabs the game board, and tosses it out the window, apparently taking Lincoln's words too literally.
With the plan revealed, Lynn asks her siblings why they wanted to lose. Lincoln replies that they wanted to lose so she can win, in hopes she would stop being competitive. Lynn says that she was being competitive because she wanted to regain her edge after losing. Lisa and Luna further explain that the reason she lost was because of the fact that all of the siblings teamed up and were going against her, because after 300 wins, they couldn't take anymore of her gloating. With all this information, Lynn apologizes to her siblings for the way she acted, and promises that if they give her another chance, she'll stop being a bad winner and sore loser, and start being a good sport, to which the siblings agree to.
Later, Lynn wins a card game, and instead of rubbing her victory in front of everybody's faces, she tells them "good game", and leaves. She heads outside, and walks over to the driveway, where she suddenly begins showboating. The other siblings look out the window, and despite Lynn showboating as usual, they're fine with it, because as Lincoln says, "At least it's not to our faces."
During the production of this episode, there was an earlier version of the story, because the episode was originally going to be directed by Kyle Marshall, instead of Chris Savino. However, somewhere down the line, Kyle Marshall stepped down from directing the episode, and because of that, certain elements that were supposed to appear in the episode were cut out as a result. This was confirmed on an Instagram post from the episode's storyboard artist, Miguel Puga. 
On the title card:
Although Lincoln himself doesn't appear, the orange game piece represents him, because it is his theme color, and the remaining game pieces represent his sisters, because of their theme colors.
So technically, this counts as Lincoln's "appearance", as the show has a tradition of having Lincoln on every title card.
This, in turn, is the first title card that doesn't have anything that physically resembles Lincoln.
The dark blue and pink pieces, which represent Lana and Lola, respectively, are placed together, since they're twins.
Because the episode puts a lot of emphasis on Lynn winning board games, the red game piece (which represents Lynn) is placed on a winning space.
This episode might take place before "Hand-Me-Downer", because the bike Lynn used to chase her siblings in the van was her BMX bike.
This episode's promo image depicts the Loud kids as a trophy statuette. This was previously shown on the title card for "Making the Case", where Lincoln was a trophy statuette.
In the original storyboard, when Lynn was brushing her teeth, instead of losing a tooth, her gums would start bleeding from the excessive brushing.
This episode shows that Lynn is good not only at sports, but also at board games.
In the beginning of the episode, Lynn refers to Lincoln as "Stinkoln", the nickname given to him by the girls' male counterparts in "One of the Boys".
According to Lisa, she says that the chances of getting all 10s with three twenty-sided dice is 1 in 1,720.
Considering the way she was speaking, the number was probably going to be higher and end between 1,721 and 1,729, but Lynn interrupted her with her lucky roll.
When Lynn lost her tooth, her appearance was similar to her original character design.
Irony: The Loud kids thought Lynn losing would make her gloat less, but it ended up making her gloat even harder/more than ever.
Lynner Takes All - The title of this episode is a pun of the phrase, "winner takes all".
Wilhelm scream - When Lynn pushes the door on Lincoln, the Wilhelm scream can be heard.
Hasbro - Some of the board games the siblings play are references to some of Hasbro's most recognizable board games:
Monopoly - One of the games Lynn won at the beginning of the episode has a similar appearance to Hasbro's most famous board game.
Operation - The game Lana suggested has a similar buildup to this game, as both games involve picking up items with tweezers without touching the sides of the hole the object's in.
Toilet Trouble - It also resembles this game, both having a toilet theme.
Pretty Pretty Princess - Lola's suggested game, "Pretty, Pretty Pageant Queen", is a reference to this now discontinued game.
Stratego - One of the board games seen on the shelf is called "Strategy Game" which could possibly be a reference to this game.
Catan - Lisa's suggested game, "The Settlers of Cat-Land", is a nod to the board game, Catan, a.k.a The Settlers of Catan.
UNO - The last game the siblings played had cards similar looking to this popular game's cards.
Brandi Chastain - Lynn's victory dance and removal of her jersey at the end of this episode references an iconic victory celebration by this soccer player after scoring the winning goal for the United States team in the 1999 Women's World Cup.
The Worm - During Lynn's victory dance at the end, she does this dance move.
When this episode was first revealed, the title was spelled as "Lynn-er Takes All", but the official spelling of the episode is actually "Lynner Takes All", without the hyphen.
As Lynn was heading outside after the last game, she was missing her sideburn.
When Lynn demanded Lisa to recount the score, her eyelashes are disconnected from her eyes.
This also happend after Lynn belched at Lincoln.
This happens again at the end of the episode, when Lynn tears her shirt off.
When Lynn was shaking the die around during the rematch, there's a clacking sound heard, even though there's one die present.
At one point, one pair of Luan's eyelashes are disconnected.
When Lori says "The Lynn situation is literally the worst thing that has ever happened", the captions misspell Lynn as Lynne.
When Leni explains why she threw the game board out the window, her eyelashes are unaligned with each other.
Lynn constantly showboating.
She often says "Lynn-er, Lynn-er, chicken dinner!" when doing so.
Lynn trying to prove she's better than everyone else, even at everyday activities.
The siblings getting annoyed by Lynn's gloating.
Luan making puns that involve the word "gloat".
She says a total of six puns that involve the word "gloat".