Roserade is a bipedal Pokémon with an appearance that incorporates features of roses and masquerade attire. It has hair made of white rose petals, and a leafy, green cape with a yellow, collar-like bangle on its neck. The cape pattern reaches toward the back of its head, in spiky, sepal-like extensions on the hair. A male will have a shorter cape than a female. It has a dark-green mask over its red, yellow-lidded eyes. The lower portion of its face is light green, and it holds a bouquet in each hand. It has a red in its right hand and blue in its left. Its limbs and underside are light green. Its feet end with yellow tips.
Roserade lures prey with a sweet aroma. The more toxic its poison, the sweeter its aroma becomes. Each hand has different toxins, but both hands can jab with near-deadly power. It attacks with a dancer-like elegance, and uses hidden whips covered with poisonous thorns.
Roserade debuted in Oh Do You Know The Poffin Plan!, under the ownership of Forsythia. Forsythia first met her Roserade when it was a Budew, where she befriended it and gave it a red scarf. This Roserade, however, was very shy and timid. Roserade also protects Forsythia's garden from being ravaged by Team Rocket. It made a brief reappearance in Unlocking the Red Chain of Events! alongside Forsythia and her Lotad.
A Roserade appeared in The Rise of Darkrai. It was one of the Pokémon that had been attacked by Darkrai and later treated by Alicia in Alice's flashback of her grandmother. Specifically, it was put to sleep by Darkrai's Dark Void and then later seen listening to Alicia play Oración, alongside the other Pokémon Darkrai had attacked.
Roserade appears in Ring Around the Roserade I. Gardenia used a Roserade alongside her Cherubi in a Double Battle against Platinum's Prinplup and Ponyta. Although it quickly gained the upper hand by knocking out the latter using its poison whips and badly beat the former using combinations of Grass Knot and the aforementioned move, both ultimately became her downfall when Platinum took advantage of the cover that the knots gave and the holes that the whips created to deliver a finishing Blizzard that defeated both her Pokémon.
Roserade and its pre-evolution are the only Poison-type Pokémon in the Fairy Egg Group.
Roserade is one of the only two third stage Pokémon which can be obtained at level 1, the other being Porygon-Z.
Roserade appears to be based on a combination of a bouquet of roses, and a mysterious patron of a masquerade ball, in which masks would be worn to hide the identity of the participants. Its mask, cape and the mention of its 'movements of a dancer' in its Pokédex entry seem to confirm this.
It is also possible that, instead of roses, its design was based on hellebores, a genus in which many species are poisonous and deceptively similar to roses, tying in once again to the theme of disguises. Finally, Roserade's humanoid design, connection to flowers, and one of its Egg Groups suggest that it is also based on fairies.
Roserade may be a combination of rose and masquerade (due to the appearance of wearing a mask).