Ekans

Red / Blue: Moves silently and stealthily. Eats the eggs of birds, such as PIDGEY and SPEAROW, whole.

Yellow +3: The older it gets, the longer it grows. At night, it wraps its long body around tree branches to rest.

Gold: It can freely de­ tach its jaw to swallow large prey whole. It can be­ come too heavy to move, however.

Silver / SoulSilver: It always hides in grass. When first born, it has no poison, so its bite is painful, but harmless.

Crystal: It flutters the tip of its tongue to seek out the scent of prey, then swallows the prey whole.

Ruby / Sapphire: EKANS curls itself up in a spiral while it rests. Assuming this position allows it to quickly respond to a threat from any direction with a glare from its upraised head.

Emerald: An EKANS curls itself up in a spiral while it rests. This position allows it to quickly respond to an enemy from any direction with a threat from its upraised head.

FireRed: A very common sight in grassland, etc. It flicks its tongue in and out to sense danger in its surroundings.

LeafGreen: Moving silently and stealthily, it eats the eggs of birds, such as PIDGEY and SPEAROW, whole.

Diamond +6: It sneaks through grass without making a sound and strikes unsuspecting prey from behind.

HeartGold: It can freely detach its jaw to swallow large prey whole. It can become too heavy to move, however.

Y: Moving silently and stealthily, it eats the eggs of birds, such as Pidgey and Spearow, whole.

Omega Ruby / Alpha Sapphire: Ekans curls itself up in a spiral while it rests. Assuming this position allows it to quickly respond to a threat from any direction with a glare from its upraised head.

Ultra Sun: By dislocating its jaw, it can swallow prey larger than itself. After a meal, it curls up and rests.

Ultra Moon: The eggs of bird Pokémon are its favorite food. It swallows eggs whole, so sometimes an egg gets stuck, and Ekans faints.