First you must evolve your Magnemite at level 30 to Magneton. Now depending on the game you are playing the evolution will vary for Magneton. Here's all the ways:
On Mt Coronet (Diamond, Pearl, and Platinum) level up your Magneton once and it should evolve to Magnezone.
In Chargestone Cave (Black, White, Black 2, White 2) level up your Magneton once and it will become Magnezone.
On Route 13 (X and Y) level up your Magneton once and it will become Magnezone.
Also in the side game Pokemon Rumble you can release five Magneton's at the Release Point for a Magnezone ticket. Optionally you can recruit it at the fire level.
take a lvl 33 or so magnemite to the inside of mount cornet and lvl it up for it to evolve.
it's easy get a magnemite (Fuego Ironworks) evolve it into Magneton (level 30) then level up at mt. coronet
-Magnaton... level magnamite up to level 30 -Magnazone.... level up Magnaton 1 level in Mt. Coronet
You can get a magnemite in New Mauville.
level up a magneton in mt cornet
Magnemite evolves into Magneton starting at level 30.
Magnemite evolves into Magneton on level 30.
go to mount.CORNET and level magnemite up, then it evolves
In Fire Red Magnemite is at the Power Plant.
you have to trade it from Diamond/Perl/Platinum.
you cant find it you have to evolve magnatone
Magnemite cannot breed unless it has evolved to Magneton or Magnezone.