Heliolisk is a bipedal Pokémon that resembles a yellow lizard. Its head is mostly black with a yellow lower jaw. It has blue eyes with a pointed spike over each. Covering its neck is a black frill with orange spikes around the rim. This frill can be raised to frame its head if needed. Its hands and feet are black with three digits each and there is an orange band with triangular markings around each leg. It has a long, tapering tail that is orange and then black at the tip.
Heliolisk can generate sufficient electricity to power a skyscraper, simply by flaring open its frill. When its frill is flared while it basks in the sun, it can generate enough electricity to power an entire city. This electricity can be used to stimulate its muscles, which boosts the strength in its legs. This allows it to sprint a hundred yards in five seconds. In Galar, there was an old desert culture that highly treasured the Heliolisk due to treasure having arrived with them. Prior to Generation VIII, Electrify was its signature move.
Heliolisk is likely based on a frilled-neck lizard, because of its notable ability to expand its frill. With its frill fully expanded, Heliolisk also resembles the sun itself when viewed from the front; its black coloration may possibly be a reference to solar eclipses. It may also be based on the spotted salamander, a salamander that has the ability to photosynthesize. Its English name, bipedal stance, and ability to learn Surf (and run on water in New Pokémon Snap) are likely inspired by the common basilisk. Heliolisk's ability to convert solar energy into electricity along with its title as the Generator Pokémon suggests that it may have been inspired by the solar power generation system. Its French name suggests it may be based on the iguana. Additionally, it shares few resemblances to the leopard gecko and the Dilophosaurus, a genus of theropod with two crests on its head, commonly yet inaccurately depicted with frill on its neck.
Heliolisk may be a combination of ἥλιος helios (Ancient Greek for sun), basilisk, and possibly obelisk (ancient Egyptian monument that represented a ray of sunlight piercing the clouds and hitting the ground at a ninety-degree angle).
Elezard may be a combination of elekiter, 襟巻蜥蜴 erimaki tokage (frill-necked lizard), and lézard (French for lizard).