Depending on who it is, you still have to beat the Brain.
Fire Emblem is not in Pokemon Emerald.
somewhere in their base
go to mount pryre.
You do not need and you cannot get the Magma Emblem in Pokemon Ruby. The Magma Emblem is a story item exclusive to Pokemon Emerald.
CHIMECHEO CAN BE FOUND NEAR YOU GET THE MAGMA EMBLEM.
The Magma Emblem is used for getting into Team Magma's base in Pokemon Emerald Version.
In 7th gym
Go to the Pokemon league.
mossdeep city
the man on mnt. pyere gives it to you af ter you beat them on mnt. pyere
In Pokemon Sapphire, Ruby and Emerald the 7th Gym that's located in Mossdeep City has Psychic type Pokemon.
Any Pokemon with ice or electric moves