- Awesome Music: As per Kirby tradition. What's surprising is that several tracks from Kirby Air Ride were remixed. What's not surprising is that the composer, Shogo Sakai, also worked on the soundtracks for games such as Kirby Squeak Squad, Kirby Air Ride, and MOTHER 3.
- Bizarro Episode: 4-10 and 4-11. In Volcano Valley, a fire-haunted area, we have chasing after a switch taken by astronaut monkeys, building a spaceship from a puzzle, Space Is an Ocean, monsters that create black holes, gravity switches in another space station run by said monkeys...
- Breather Boss: Lady Ivy, the second world's boss, which is just insultingly easy after the hassle of getting the gold star from Whispy Woods in the previous level. Provided you can figure out that this is pretty much the only boss that dragging makes easier.
- Skullord is disappointingly easy, especially after Buzzy Bat...
- Broken Base: While the game itself is good and many people think it's interesting, quite a few feel the games main gimmick of controlling multiple Lilliputian versions of Kirby could have been better used with a series where it made more sense, such as the Pikmin series.
- Demonic Spiders: Which are actually giant spiders in this game.
- Ensemble Dark Horse: Daroach, who returned for this game likely due to his popularity in Squeak Squad.
- Goddamned Bats: Even though the Zombons in Volcano Valley, which are zombified Beanbons, are easy to beat, they just keep coming back.
- Moral Event Horizon: Necrodeus splitting Kirby into ten smaller Kirbys and trying to kill them (one little Kirby escaped, thankfully).
- Making this even worse is that we are given absolutely no indication as to whether Necrodeus was trying to preemptively remove Kirby as a threat or just committing random murder for kicks. Given that his name means "death god", the latter is extremely plausible. Also, Daroach hints that Necrodeus despises beings of light, which presumably includes Kirby.
- Player Punch: Anytime you let every Kirby get killed, the Warpstar trembles and explodes, and then you see Kirby's ghost about to ascend to heaven in the game over screen. This starkly contrasts with the comical and non-consequential game over scenarios from about every other game in the franchise, and can feel rather depressing if you're sentimental for the character.
- Scrappy Mechanic: In this game, Kirby has a limited air meter for breathing underwater that must be replenished with air bubbles, which probably doubles as a Shout-Out to Sonic the Hedgehog. Yes, this is as annoying and frustrating as it sounds, and it gets even worse later when you have to swim in toxic water that drains your air meter twice as quickly.
- Sidetracked by the Gold Saucer: Kirby Mass Attack features quite arguably the most expansive set of sub games of any Kirby game. The various games are quite diverse, ranging from pinball, to on-rails shooting, RPG style combat! Not only that but they feature many anime characters and a menagerie of Kirby references. These games can be quite addicting and can easily overshadow the main game in replayability. In fact, it's a common sentiment amongst Kirby fans that Mass Attack's sub games are outright better then the main game.
- That One Boss: Some players agree that some of this game's bosses are so damn hard it's not even funny. King Eelongo, which is basically flinging Kirbys at underwater moving objects that are spiky almost all over, requires some dexterity. This is one of the more infamous examples.
- Interestingly enough, as far as gold stars go, the toughest world boss is the very first one, Whispy Woods, as the timing to attack him without him countering and hurting you in the process is very minuscule. Otherwise, he falls straight into Wake-Up Call Boss territory.
- Level 4-9 counts for this in its entirety, especially the last part. Just read below.
- While this is part of 4-9, Buzzy Bat deserves special mention. He's the last miniboss in the game for good reason; the fight deals with breaking his shield of bats and finally hitting him, which instantly destroys the whole shield as you start beating him up. If you take too long, he combines with the shields to form a monstrous cycloptic bat that you can only run from and wait for to break. As you go on, the shields become more complex and starts to add giant, invincible, spiked bats. The final shield has three of them and small openings to actually attack the main bat.
- Mr. Shine and Mr. Bright in Strato Patrol EOS. It's a Dual Boss where you have to deal with Mr. Bright firing rather big lasers at you or giant circles of energy at you while Mr. Shine becomes invincible and spins throughout the room. Oh, and if you kill Mr. Bright, Mr. Shine proceeds to revive him. And if you kill Mr. Bright four times, Mr. Shine proceeds to merge with the remnants of Mr. Bright and goes berserk, firing lasers at fast speeds and spinning in a new fashion. Meta Knight later on is also pretty tough, especially when he charges throughout the room. And you fight Nightmare, the Final Boss, immediately afterwards.
- That One Level: For anyone playing this game and trying to get 100% Completion, which has a task of beating each level and the bosses without getting hurt to get all of the gold stars, you should know or remember these levels:
- Level 3-6: This level is very long with tons of enemies, and is very easy to hit while trying to play through it. And it only gets worse, as it has a difficult underwater boss fight at the end. Keep in mind that this is one of the only times Kirby has a limited air meter for breathing underwater that must be replenished with air bubbles, and you'll realize the hardest part of this whole ordeal.
- Level 3-11: This is more due to Fake Difficulty than anything else, as you're in a giant tree that's swaying back and forth depending on which side you move the Kirbies to, and you have to move quickly to avoid leaning the tree in one direction too long and causing the whole tree to topple over (resulting in an instant death). The hardest part in this level is around the halfway point, where you have to carefully dodge several rows of spike balls followed by a giant spike ball afterwards, which is almost impossible to do while moving all of your Kirbies upward. Fortunately, if you can make it past this sequence without getting hurt, the rest of the level is much easier.
- Level 4-9: This is the last level for a very good reason, as it's the single hardest gold star in the entire game to get and hard enough just to beat normally. It starts in a graveyard with three familiar pictures on the graves you pass. You eventually reach a fourth gravestone with a new image on it and push it aside to reveal a passage that leads into a room under the first three tombstones you passed and see three doors as well as a fourth door that's locked until you investigate the first three doors. In each door is a boss that you previously defeated, which include the giant worm Big Warwiggle, the ancient gear Great Gear, and the wooden fish King Eelongo (in toxic water no less, which causes you to lose your air twice as quickly), all resurrected and even stronger than before. After you go through all three doors and open the fourth door to reach the exit, you are attacked by the boss of this area, whose picture was on the fourth grave outside. This boss, Buzzy Bat, is a giant bat who is almost impossible to beat without getting hurt, even with lightning fast reflexes, and thanks to Fake Difficulty, landing the final hit on him without getting hurt is basically a game of luck. Getting this gold star will probably take many tries even if you are skilled, but if you can pull this one off, you can get all of the other gold stars easily.
- That One Sidequest: Completing all of the list objectives with "Gold Star Champion" standing out as the toughest one due to the fact that you have to beat each level and the bosses without getting hurt to get all of the gold stars.
- Unexpected Character:
- No one really had any idea that literally any character from Kirby: Right Back at Ya! would appear in any Kirby game until they played the sub-games.
- Daroach and the Squeaks also came as quite a surprise as one-off characters rarely had recurring roles in the series prior to this game's release. This could also be extended to Marx, Bandana Waddle Dee, Sailor Waddle Dee, Nightmare, and Dark Matter who all had little to no recurring roles the series after their initial debuts at the time the game came out.
- The Woobie: Kirby, much more than usual in this game.
YMMV / Kirby Mass Attack