Well, this may be simple, but anyway...

Earth and Water,
Wind and Fire,
This the order must be.
Rising once before receding.
Once again after thee.

One atop a mountain high,
Guards the Passage of Light,
Another on the throne resides,
Barely seems to make a fight.

The third in a great tower lives,
Floating high above the air,
The Final is a gentlemen,
Always wanting to fight you fair.

Who are they?