3rd Gen 'One-Time' Visit Areas

[mattfeeder18]

In my RSE/FRLG games, I wish to, when I complete them again, search in all the areas for hidden items, with help from the good old Itemfinder.

Basically, I want to know the areas which arent accessable ever again after certain points in the game.

All I know at the moment are:

The Van at the very beginning of the game - Once you exit the vehicle you cant get back in, then it disappears when you are next outside (Ruby, Sapphire, Emerald)
Mirage Tower - Disappears when you pick Claw/Root Fossil (Emerald)
POSSIBLITY BUT NEED CONFIRMATION - Aqua/Magma Hideouts - Un-enterable when you defeat the leader then do something else which I dont know of - I THINK (Ruby (Magma), Sapphire (Aqua), Emerald (Both))

I dont know any in FireRed and LeafGreen.

Does anyone know of any other areas which are unavailable? Thanks alot.

 

[Ivysaur]

In Emerald you can enter both hideouts whenever you want.

In fire red? The SS. Anne- Goes when you get Cut (unless you lose in the ship, or get cut by trading a pokémon with it)

 

[JX Valentine]

In fire red? The SS. Anne- Goes when you get Cut (unless you lose in the ship, or get cut by trading a pokémon with it)

I've tested this by losing in the ship and going back much later in the game. Maybe it's just because I came back after I got the passes for the Sevi Islands, but when I tried, the SS Anne was gone.

So, perhaps up until a point, you can get to it for a second time, but I'm not entirely sure it leaves just when you step off the ship.