Smash Bros. room
A Smash Bros. room[conjectural title] is a room that serves to provide Kirby with the Smash Bros. Copy Ability via a Copy Essence exclusively in Kirby: Planet Robobot. These rooms are important as the copy ability cannot be obtained from any enemy in Kirby: Planet Robobot. The only other ways to obtain this ability are either to scan the Super Smash Bros. series Kirby amiibo into the game, or use the Copy Ability Testing Area.
There are five Smash Bros. rooms in Kirby: Planet Robobot. Although these rooms are hidden, with the exception of one, they are not HAL Rooms. These rooms have some things in common; all of them are relatively small and tucked away, they are all accessed through hidden doors, and all of them are not required to complete the stages they are located in. The rooms are not entirely optional, as two of them contain unique Stickers required for 100% completion of the game.
Patched Plains - Stage 4
In the first room of Patched Plains - Stage 4, after passing by a Spynum and the first column of four Cracked Blocks, Kirby will face some metal platforms with gaps between them. Under the leftmost metal platform (suggested by a missing part on it) is a hidden door that leads to a room containing a Copy Essence of the Smash Bros. ability, and a lone Labotory. In the top-right corner, there is a Bomb Block, which when detonated releases a 1-Up from the ceiling. The way of accessing this room is a reference to a hidden room in Vegetable Valley - Stage 1 which contains the UFO ability.
Overload Ocean - Stage 1
At the bottom right corner of the first room of Overload Ocean - Stage 1, there is a submarine with an opened door that leads to a partially underwater room. Kirby must break through some cracked blocks to reach the Copy Essence. The only enemies in the room are two Squishies. There are three Bomb Blocks, which reveal some Point Stars, a Sticker, and a Maxim Tomato.
Kirby swims for the Copy Ability above him.
Rhythm Route - Stage 2
In the first room of Rhythm Route - Stage 2, at the top of the casino, there is an open window. Entering it will bring Kirby to a small vertical room. After climbing down a ladder, Kirby can find the Copy Essence for the Smash Bros. ability. Underneath the Copy Essence, there are many Star Blocks. Breaking them reveals a unique Sticker, some Food, and many Point Stars.
Access Ark - Stage 1
After defeating the second Security Force of the stage, Kirby must enter a hidden passageway at the top right corner of the screen. At the other end is a small room which contains some Point Stars, a 1-Up, and two portraits of President Haltmann. The right portrait has a tear at the top right corner, which can be entered as a door. The next room also doubles as a HAL Room, as it contains large Star Blocks in the shape of the letters 'HAL'. A single Haltworker sits atop the L, in place of the usual Broom Hatter. Alongside the Smash Bros. Copy Essence, the room also contains all three of the new Copy Abilities introduced in Kirby: Planet Robobot, those being Poison, Doctor, and ESP. If Kirby breaks the Star Blocks, he will reveal many point stars, a Maxim Tomato, and a Sticker.
Access Ark - Stage 5
After Kirby crashes his Jet Armor at the end of Access Ark - Stage 5, if he hovers up above the warp portal instead of entering the cannon, a secret door can be found inside of one of the stars used as decoration. Taking this door leads to a Tilt Cannon puzzle. The fourth cannon gives Kirby a choice between three paths. The left path contains a unique Sticker and a cannon which will launch Kirby back up. The right path is the "wrong path", which will send Kirby straight into a warp portal to the next room. The center path leads to a small room containing the Smash Bros. Copy Essence and a cannon which leads to a warp portal to the next room. Ideally, the left path should be chosen first as it will send Kirby back up after he gets the sticker and will give him another go.
- With the exception of the fifth room, all of the Smash Bros. rooms are located at or near the beginning of the stage, as the Smash Bros. ability can then be used to get through the stage easier. This allows players to get the ability quickly and then leave for a different stage.