Fomantis is a small, plantlike Pokémon. It has large, dark pink eyes with slightly darker pupils. Bunches of light green leaves surround its head, and a particularly large tuft in front slightly overhangs its face. A small, dark green bulb sprouts from the center of its head, which emits a pleasant aroma. Around its neck is a collar of short, dark green leaves. Extending from its collar are four lighter green leaves with white tips: two in the front and two in the back. In the front, these leaves act as scythe-like arms. Its main body is pale pink with a thick, dark pink stripe down the front and back. It has a stubby tail and two short legs.
In order to achieve evolution, Fomantis stores up energy gathered by photosynthesis. It is nocturnal, so during the day, it spreads its leaves wide to catch the sunlight. During the night, it spends its time searching for a new spot to sleep for the next day. It will not stay in the same spot for more than a day due to the danger involved. If anything bothers it while it is gathering sunlight, Fomantis will fiercely attack it. When regularly exposed to sunlight, it grows up with vivid coloration. Though it excels at long-range attacks, it will rarely use those that require it to use its stored photosynthetic energy. Fomantis can give off a sweet and refreshing scent. Bug Pokémon like Cutiefly are known to gather near it due to its scent.
Fomantis may be based on the orchid flower along with the orchid mantis, reversing the mimetic relationship between those two organisms.
Fomantis may be a combination of faux (French for both false and scythe) and mantis.
Karikiri may be a combination of 仮 kari (pseudo-), 刈 kari (prune; trim), and 螳螂 kamakiri (praying mantis).