Original release date: September 24th, 2020 [Most regions] - September 23rd, 2020 [NA] - December 10th, 2020 [S.Korea - Physical download code version]
Studio: HAL Laboratories, Nintendo, Vanpool
General Director: Shinya Kumazaki
Original platform: Nintendo Switch [Eshop exclusive]
Platform I played on: Nintendo Switch [Digital copy]
Date finished: July 9th, 2023
Completion: 100%

Plot + Gameplay

The game itself isn't just about story, but it does have a Story Mode.
King Dedede and Meta Knight are still lowkey salty about not being able to beat Kirby so they teamed up and invited Kirby to climb the Buddy Fighters Tower for a 2v2.
Kirby can't read, but he shows up anyway.
There's a couple of fake-outs, but you will evetually fight Dedede and Meta Knight.
After you beat them once, they run off and you gotta beat them again. After you do that, the credits roll, but the story mode isn't over.
This time they decide to use the Mask(s) of Dark Bonds after Phase 1 to power themselves up. You still beat them though and get a nice little epilogue and another credits roll that I recommend you do not skip, because the music is really good, and there's short little cutscene after it. Honestly, same goes for the first credits roll.
The story isn't mindblowing or anything, but it serves it's purpose, and also gives us some insight into a relationship not involving Kirby directly. There hasn't exactly been that much canon interactions or information about Dedede and Meta Knight's relationship before this aside from Meta Knight being Dedede's friend/underling in Adventure/Nightmare in Dream Land.
Then this game came along and the MetaDede ship exploded in popularity lmao.
In Chapter 4 their boss title refers to them as Sworn Partners, which should describe their relationship pretty well. They're very good friends with a strong bond, or married, depending on who you ask. I don't have a horse in this race, I like them regardless. It's also nice to see them have actual team attacks and not just 'now you fight two people at the same time'. Shows that they actually have a bit of synergy. I'd love to see more of that in all games where you fight a duo of supposed friends.

Kirby Fighters 2 is a fighting game. I don't play fighting games, so I can't really review it on how good it is as a fighting game, but as a Kirby game, it's okay.
There's a few different game modes you can play. You can fight against folks online or locally (I think?), I don't play multiplayer so I can't say much about that, you can fight against CPUs with your chosen difficulty, you can do the story mode, the final chapter being basically a roguelite, or you can play... the single-handed mode.
I'll be honest, I fucking hate Single-Handed mode, purely because beating all difficulties once and beating hard with all copy abilities/character was a requirement for 100% completion.
It was actual fucking hell and I wish whoever decided that that should be a 100% requirement a very kindly-go-fuck-yourself.
Aaaanyways, you have a little exp bar and when it fills out, your Fighter Rank goes up, and when it goes up you unlock stuff. Unlockables include new abilities/characters, outfits, perks for story mode, stages and songs.
All copy abilities have 3 different outfits, some have more (I believe the additionals were unlockable by having Star Allies and Super Kirby Clash save data?), unfortunately the other characters you can play as (Bandana Dee, Gooey, Magolor, Dedede, Meta Knight) don't have alternate outfits.
You unlock Meta Knight as a playable character by beating Chapter 4 for the first time, and Dedede by beating the Final Chapter for the first time. The others you unlock with Fighters Rank.
The fighting itself is... well, Kirby combat, with some adjustments from the main game, such as Magolor being at least a little bit nerfed from Star Allies.
You can't fight ability-less, but there's plenty to choose from; Sword, Staff, Bomb, Archer, Artist, Beam, Hammer, Water, Parasol, Beetle, Bell, Cutter, Ninja, Whip, Yo-yo, Fighter and the (so far) Fighters 2 exclusive Wrestler.
Some are definitely better than others, but ultimately, even 'bad' abilities can be good depending on the situation, or if you just get good at using them. I watched an entire video about how Bell was the worst ability in the game, yet I beat Single-Handed Mode on very hard relatively easily with it.
As for how the different game modes go, Battle Mode is basically 'choose your own adventure' for battles against CPUs, in Single-Handed Mode you go against 8 waves of opponents by yourself and then fight Shadow Kirby as the final boss. Shadow Kirby has the same ability and outfit as you do. He's also an absolute pain in the ass 99,9% of the time, in my experience.
And then there's Story Mode, my personal favourite, and easily what I've played the most. You pick an ability, outfit, a buddy (can be CPU or locally controlled), maybe even an outfit for your buddy if they're another Kirby, choose the Chapter you want to play and then you take on Floors of enemies like in Single-Handed mode, and even the occasional boss fight.
Sometimes Floors are special, for example, in Speedy Stages, everyone has double movement speed for the entire match.
Between each Floor, you get an Item Room where you can pick a perk that will last you (and your buddy) for the rest of the Chapter (unless said item is Healing Food). The perks can be anything from a simple stat increase, to taking less damage from environmental hazards, to trippling the amount you heal between floors, but preventing healing food items from appearing in battle or Item Rooms.
The items are random every time you play the chapter, some may not even show up for an entire run.
During battle, a bunch of items may fall from the sky. Can be anything from Mike that does a shit ton of damage to nearby opponents to Invincibility Candy to Mint Leaf (or Roasted Sweet Potato in Japan apparently), which let you attack with air bullets.
Much like in the main series Kirby games, the effects of Healing Food, Invincibility Candy and Mint Leaf can be shared with your buddy for a short while after you get it.
Unlike in the main games however, you can't revive your friend if they go down, instead, after a while they respawn as a ghost, and can revive themselves if they manage to hit an enemy. Same goes for you. How fast you become a ghost, how fast you move as a ghost and how much HP you recover can be increased with Ghost Stones you get from item rooms. You can also entirely disable ghosts for yourself and your enemies with a Cursed Anti-Ghost Ring.
From Chapter 4 and onward, you'll face Shadow Kirby on occasion, twice in the Final Chapter. He'll have the ability and outfit matching either you or your buddy, depending on the encounter.
He's usually a bit less of a pain in Story Mode since you have someone helping out now.
In chapters 1-4 you have infinite tries, you just loose points if you loose the match and then get to try again, but in the Final Chapter, you only get 2 losses (3 tries) for the ENTIRE 50 Floor chapter. If you run out of tries, it's permadeath and you start all the way from the beginning of the chapter again.

Things required for 100% completion: Beat all of Story Mode at least once, beat Chapter 4 or 5 (final) with all abilities/characters, beat all difficulties in Single-Handed Mode at least once, beat Single-Handed Mode on hard or very hard with all abilities/characters at least once, reach Fighter Rank 100.

Graphics + Music + Sound Design

The game looks great, which is to be expected for a Kirby title on the Switch. A lot of the battle stages are yoinked from earlier games, and given a bit of polish, to fit better with modern Kirby graphics.
It's very easy to see what's part of the background, and what actually matters during the battle.
The music is excellent, which again, is expected of a modern Kirby title.

The soundtrack includes both new and old tracks as well as full on remixes. I especially like the more traditional Japanese instruments that most of the Story Mode boss themes, and some stage themes have.

The sound design is pretty much on par with other Switch Kirby games, aka, does it's job as it should. You can pretty easily tell what's going on based on the sound effects alone.
The sound of hitting an opponent your partner yeeted at you, combo-ing them and doing big damage is satisfying, as is kicking their skulls in with something like Wrestler. You'll also definitely know if someone landed in lava or got K.O'd.
Depending on which outfit you choose for Bell, you'll have a slightly different sound for your attacks, which is neat.
Sometimes the audio may sound a bit odd when the battle ends, such as if a bomb explodes right as the battle ends, but I find that more funny than anything else.

Easter Eggs + Other Fun Stuff

I encountered a glitch in Story Mode where I'd picked the Cursed Auto-Heal Ring, preventing healing items from spawning in battles or Item Rooms, but still got a healing item in an Item Room.
Assumably this is because I picked up an Item Selection Plus, an item that adds 1 item to Item Rooms, after the Ring, assumably overwriting a part of the Ring's effects.

Other Stuff

100%ing this game single-handedly made me more livid than anything else in my entire life so far.

My Enjoyment of the Game/Thoughts

My enjoyment depends a lot on the mode. Battle Mode I find a bit boring, I generally enjoy Story Mode, even if I get a little tilted in the Final Chapter sometimes, and I despise Single-Handed Mode with my entire being.
Genuinely, having to deal with the bs of Single-Handed Mode did dampen my enjoyment of the game overall a bit because I'm petty and hold grudges against fictional characters apparently.
Ultimately, everyone's experience is gonna be different, but I still cannot wholeheartedly recommend you try to 100% the game. Unless you're good at fighting games (or better than me anyway) or hate yourself.

Score: Before attempting 100% completion: 6/10, after doing 100% completion 5/10

Images are from Wikirby and belong to Nintendo/HAL Laboratories