Hello! I would like to know if I need to be in the Halloween Event map in order to catch Event Pokes, or can I just hunt them in their regular spawn? For example, I was hunting Charmander in Cinnabar Island and when I told in All Chat that I haven't found anything yet, they told me to go to Halloween map.

Hello,

 

Halloween event forms can spawn in any location the Pokémon normally spawns in. The sole exception is Pinkan Island where event forms will not spawn.

 

Hope this clears things up. If you have more questions, please let me know

The forms can spawn anywhere the pokemon spawns. The event map is better better due to being able to hunt for multiple pokes with form at the same time.