You'll need a Thunder Stone to make it evolve.
You can evolve Eelektrik by using a thunderstone.
Evolve it using an Thunder Stone.
It evolves with a thunderstone not levels
Tynamo evolves into Eelektrik starting at level 39. Eelektrik evolves into Eelektross by using a Thunderstone.
Eelektrik, Pikachu and Eevee are the Pokémon that can evolve once you use a Thunder Stone on them.
The only new one to use thunder stone is Eelektrik to Eelektross. Then you have your Pikachu/Raichu and Eevee/Jolteon.
level 50
Eelektrik - Eelektross
You can't find Eelektrik. You have to evolve a tynamo, which can be found in Chargestone Cave (it only has a 2-8% appearance rate)
Tynamo evolves at level 39 into Eelektrik.
Eelektrik evolves into Eelektross when you use a Thunderstone on it.
Tynamo evolves into Eelektrik at Level 39.