You can't
it's in pokemon leafgreen
no.
There is no such Pokemon as a magma. If you mean MagmaR, no
After Team Aqua and Team Magma return the orbs in Pokémon Emerald, you can find them in their respective hideouts. Team Aqua is located in the Aqua Hideout in Lilycove City, while Team Magma can be found in the Magma Hideout in Fiery Path. After dealing with them at these locations, you can also encounter them in the Sky Pillar as they attempt to awaken Rayquaza.
Team Magma Hideout
you can find him at the top of the volcano a couple gyms after you fight the leader of team magma
On Mt Chimney to find it you need a magma emblem which you will get on Mt Pyre.
You will need to defeat the Team Aqua or Magma grunts in the Seafloor Cavern and make your way though their ranks to the leader of Team Aqua/Magma.
he is at meteor falls with a few team magma members he gives the team magma members a meteorite the Archie and team aqua shows up team magma runs away then prof. Cozmo gives you something and then you have to go to mt. chimney and fight Maxie
This is not the team magma cave that is team aqua cave. Team magma cave opens when you have the magma symbol.
just go to mt.ember on island 1 and search in the grassy areas its not easy to find tho good luck!
In the mountain after defeating the team magma leader.