Latias' sign looks exactly like Latios' sign except upside down.
There is no sign for meganuim.
latias is in Pokemon ranger signs.
The Latias sign looks like a sign. But you cannot register it until you have visited all the islands.
then its not latias its latios
no regigigas does not
he is in the sky
rasp cavern
pokemon originaly came from there mother
in the cave of icicles
yes
it is in daybreakruins i think
you never use it
you go there at the start of the game