Its evolves at level 20. A few ways I have evolved mine are using a Exp Share. If not you must keep Magikarp as the party leader and switch on the first turn.
Magikarp will begin to evolve into Gyarados once it reaches Level 20.
train it train it
By levelling, it evolves at Lv20.
In Pokémon Ruby, Magikarp will evolve into Gyarados at Level 20.
magikarp evolves into gyarados at level twenty in any Pokemon game.
Lv20
level 20
Simply level it up to 20.
A Magikarp should evolve at about lvl 40 on Pokemon diamond
Magikarp can evolve into Gyarados, starting at level 20.
Magikarp evolve at level 20.
You evolve it at level 20
Get the Exp. Share and let your Magikarp hold it. When you battle, use a strong Pokemon and Magikarp will get some Exp. That's how I got my Magikarp to Evolve.
In Pokémon Ruby, Magikarp will evolve into Gyarados at Level 20.
No, Magikarp cannot evolve in the Daycare in Pokémon Ruby.
20
magikarp evolves into gyarados at level twenty in any Pokemon game.
level 20
Lv20
it evolves at lvl 20