it is inside union cave sootopolis city hanit
You must obtain Deoxys from Birth Island in Emerald.
by beating volkner
ice path
in Pokemon emerald is there another way to get the skill tag than on mirage island
petroleum waterfal
You cannot obtain it in Emerald, you must trade from LG or FR.
you can find a skill tag on mirage island.
The last gym leader gives it to you
You can't catch or obtain other trainers Pokemon in emerald.
No. You can not obtain exeggcute in emerald. The only way is to trade from FR/LG.
you cant
You can obtain any Pokémon you have captured on the Emerald cart, but you need to go to the pal park to release and re-capture them.