Resembling greatly both a UFO and a jellyfish, Dubior has an upside-down bowl shape to its ivory, head-like section, featuring a black rectangular screen through which its circular, glowing yellow eyes are visible. Its head also features two grey semi-circular panels on either side, as well as a bent, umber antenna on top, which itself carries three horizontally parallel strips that move around as Dubior does whilst changing color; resting usually as yellow, shifting through to red when attacking, and turning cyan when commanding Dubior Jrs.. Below its head is a round, scarlet underside, surrounded by five ivory and orange bullet-shaped floating appendages. These spin around Dubior rapidly.
Dubior's Extra Mode counterpart is pink in color and has only one eye. The underside of its head is now cerulean, and the tips of the revolving appendages around it are pink as well. Dubior EX has more health and its attacks deal more damage than the original's. Fitting Kirby: Planet Robobot's Extra Mode boss and mid-boss variant naming scheme, Dubior EX has its name changed to Dubior 2.0 in that game.
Dubior's attacks include a charged ram that deals lots of damage, a lightning-bolt attack from above that strikes repeatedly, and the ability to spawn and direct Dubior Jrs.—miniature missile-shaped versions of itself (two in the main game and four in Extra Mode) which will zigzag around the screen and may be inhaled to obtain the Spark ability. A great opportunity to strike is right after the charged ram, due to the fact that it will remain incapacitated momentarily following the attack. When weakened, it will shoot several orbs of electricity from its bottom at Kirby. Even just moving around is a form of attack for Dubior, as it will zip about at random locations above Kirby's head. Dubior is usually fought before a puzzle that requires the Spark ability to complete it. Many of Dubior's attacks are similar to Kracko's and Kracko Jr.'s.
Dubior EX is a lot more unpredictable in battle. It darts around in the air much faster and charges more quickly. The charging attack is altered; sometimes instead of just charging ahead in a straight path, Dubior EX will loop in the middle of its ram to attack the player character if they try to jump. The Dubior Jrs. it spawns are more numerous than before and make it harder for Kirby and his friends to avoid their flight patterns. Dubior EX can now use an altered version of its lightning-bolt attack. Instead of striking repeatedly, it sometimes fires along the ground and moves toward the player, much like Kracko's signature attack. It will do this twice in a row, pausing for a second before moving towards the player for a second strike.
- Dubior's normal coloration may pay homage to R.O.B..
- Dubior bears a bit of a resemblance to a mechanical version of a mid-boss from Kirby's Dream Land 2 named Master Green. Both are a shade of yellow (Master Green in his artwork) and give the same ability (Spark). The detached parts of metal that encircle Dubior's body somewhat look like short tentacles, further adding onto its appearance of a robotic jellyfish.
- Dubior is the only mid-boss in Kirby's Return to Dream Land (excluding the Sphere Doomers) that is never fought with Planet Popstar's mid-boss theme playing in the background. The only Popstar stage it appears in is Stage 5 of Nutty Noon, where King Dedede's Theme plays.
- Gigant Edge is the opposite of Dubior in terms of the mid-boss music. It never plays Halcandra's mid-boss theme but will always play King Dedede's theme in its second-to-last appearance. It does appear in Dangerous Dinner, but only during Kirby's Ultra Sword rampage in Stage 3, during which a remix of the Super Ability theme will pay
- Dubior EX vaguely resembles Javelin Knight, one of the Meta-Knights.
- Dubior is the only returning mid-boss In Kirby: Planet Robobot not to have a mechanized redesign, likely due to the fact that it is already a machine.
- In Kirby Star Allies, when playing the Guest Star ???? Star Allies Go! sub-game as Magolor, some stage layout in Level 5 is changed to reflect Stage 3 of Dangerous Dinner from Kirby's Return to Dream Land. Dubior is represented by Anger Maskers.
- ↑ Kirby's Return to Dream Land file name