Toxapex is a small Pokémon with large, starfish-like tentacles sprouting from the top of its head. It has bright blue eyes with yellow sclerae and pupils. Its main body is a dark purple and consists of two sections: its head and lower body. Its head turns dark blue on top where the tentacles connect, and its lower body has triangular protrusions extending in all directions. Additionally, its body is typically suspended due to the length of its tentacles.
The tentacles themselves are light blue on top and covered with spines and dark blue with pinkish-purple spines on the undersides. When the inner spikes are present, the outer spikes sink back into its tentacles, and vice versa. The tip of each tentacle has two yellow claws, and there is a ring of yellow spines around a pinkish-purple marking where all the tentacles meet on top.
Toxapex uses its 12 tentacles as legs to walk along the ocean floor, where it hunts for Corsola. They can also be used to create a dome-like shelter from the tides. Its spines can be fired at enemies and carry a powerful poison, which causes pain for 72 hours. Aftereffects of the venom remain even after recovery. If a foe bypasses its spines, it attacks with its claws instead.