Rogue Galaxy

There are 19 different types of insector, but one of those, White Miracle, is impossible to catch. You can only battle against it. The other 18 are all catchable, though you will need to beat the Ghost Ship Extreme to get the bait needed for a Dark Emperor.

Gulza Sanctuary Plaza
Any trap will do, so long as you have a Royal Fruit from the Ghost Ship Extreme.

You can catch every type of insector except the White Miracle. It is only used as the final boss in the insector tournament. To catch the Dark Emperor, you must first beat the Ghost Ship Extreme, a side quest where you must scale 100 randomly generated floors of insaness with a tough boss every ten floors. After beating it, you will recieve the Royal Fruit. Redo the GSE to get more Royal Fruit. Place this in either Insector Trap 1 or 2, NOT 3. Then place the trap on The legendary Planet Place (Sorry, I forgot its name) and go to the Gulza Plaza then travel or warp to the Plaza part of it. Lay your trap there and wait. If you used either trap 1 or 2, and used the Royal Fruit, you will get the Dark Emperor. And this guy Pwns!