What is a Mirage-Sensitive pokemon?

There is no such thing. To get to Mirage Island, it's just a matter of luck. Each day, the game randomly picks a three-digit number for Mirage Island, and a three-digit number for all of your Pokemon in your party and in your PC.

If one of the numbers on your Pokemon matches the one for Mirage island that day, Mirage Island will appear. However, that's not very likely, as there are 999 different combinations.

So if you had 200 Pokemon altohether in your PC, you would only have a 1 in 5 chance of getting Mirage Island. To find out if you've got it, go to the man in Pacifidlog, who lives in the house on the far-right.

He will tell you if it's there or not. If it's not, go to a PC, and change your party. Then show it to the old man. if it's still not there, go get a new party, and so on. It'svery tiresome, and you probably won't get it, even if you showed the old man all the Pokemon you have.

If you're really keen though, once you've showed him all of your Pokemon, do them all again. Because once you put a Pokemon in your PC, it's number changes again.

You can't see what number your pokemon has, unfortunately. The next day, all your Pokemon and Mirage Island will get new numbers. If you are lucky enough to find Mirage Island, go there straight away, as it dissapears the next day.

Surf, to Route 130, and you'll find it. It's pretty big, so you can't miss it. All it has are some Liechi Berries, and wil Wynaut ranging from Level 5, to Level 50. Good luck.