Ekans and Arbok, in the game are not outstanding Pokemon in any area. Their qualities are average, their attacks are average, their ability to learn TMs is average, they're pretty easy to find, but the one thing that makes them different from all other Pokemon is...
They're cool! ^_^.
Ekans' Pokedex entry reads as follows:
EKANS - SNAKE - HT 6'07" - WT 15.0 lb
Moves silently and stealthily. Eats the eggs of birds, such as PIDGEY and SPEAROW, whole.
ARBOK - COBRA - HT 11'06" - WT 143.0 lb
It is rumoured that the ferocious warning markings on its belly differ from area to area.
Ekans and Arbok are catchable in the wild, only in the red version of the game.
Here is where you may find them, and the experience points you get for beating them...
In the grass before Cerulean City:
53 points for beating
70 points for beating
88 points for beating
Between Cerulean City and the Rock Tunnel:
Next to Vermillion City:
Between Lavender and Celadon City
Pokemon League building (just before Victory Road):
In Unknown Dungeon
1197 points (a good opponent to train against after beating the game)
Beyond them, Ekans is a fairly common opponent in some of the early trainers of the game.
Some trainers who have them:
A Youngster before Mount Moon. This is the first trained Ekans you will face.
A Rocket in Mount Moon has a L12 Ekans
A Youngster on Nugget Bridge has a L14 Ekans
The Rocket at the end of Nugget Bridge has a L15 Ekans
A male Junior Trainer on the path to Bill's house has a L14 Ekans
A Youngster next to Vermilion has a L21 Ekans
A male Junior Trainer on the path to the Rock Tunnel has a L19 Ekans
One of Giovanni's guards at the Game Corner has a L23 Ekans
Another Rocket guard at the same place also has a L23 Ekans
Still another of the Game Corner Rockets has a L23 Arbok
A Tamer in Fuchsia Gym has two L33 Arbok
One of the Silph Rockets has a L33 Arbok
Another Silph Rocket has a L26 Arbok
Still another Silph Rocket has a L28 Ekans
There are probably others, but those are the ones who I found and battled.
The third member of the Elite Four, Agatha, shows she has great common sense, as she has an Arbok as one of her strongest Pokemon. It's at L58 and you get 1827 points for beating it.
You also briefly see an Arbok in the closing credits for the game.
A lot of yellow info regarding the snakes is the same as the above.
These two little pics kindly sent by Team Pidgeot
There are no wild snakes to be found in Pokemon Yellow, and you can only obtain one by trading with red version. As compensation, Jessie uses one regularly. ^_^.
At Mount Moon, Ekans is the first Rocket Pokemon to be used.
Ekans, L14: poison sting, wrap, leer
At the Rocket basement, Ekans is the last Rocket Pokemon to be used.
Ekans, L25: poison sting, leer, glare, bite
By Pokemon Tower, Ekans has evolved! ^_^. It is the second Pokemon they send out.
Arbok, L27: poison sting, leer, glare, bite
In Silph, Arbok is the second Pokemon used again, and this is the last time we see him. :( Of course, Agatha has a 'bok you can see (and bash senseless ^^;;) time and time again, so it's all good.
Arbok, L31: poison sting, leer, glare, bite
I have not played these games. I tried Gold for about ten minutes, but I soon became frustrated with not understanding a word. ^^;;
I have heard that the snakes learn the attack "Haze", which is pretty cool. I like that move. It undoes status changes - heals you (and opponent) of things like paralysis, burns, or a decrease in defense, et cetera.
Here's Silver Aabo and Aabokku, courtesy of Paras13. ^_^. Both are females, you can see. ^_^.
Ekans/Arbok is not in Pokemon Snap. They are in Stadium, which I haven't really played (apparently you can throw Ekans to catch Diglett in a mini-game there), and ditto for the card Gameboy game.