Aiptasia X is really best suited for when you are dealing with a few smaller ones before they really have a chance to spread. You can't treat an entire tank worth of Aiptasia at once with the stuff (actually the instructions tell you not to). Once it gets that widespread only something that eats Aiptasia will keep it in check.
The OP, how big is the tank and how long has the Trigger been in there? The problem I see is that if the Trigger is well established it will view any new addition as competition/threat and a Copperband would be easily bullied. If the tank is big enough (ie over 200 gallons) then it is possible that the Niger Trigger will have enough space that it won't take much notice of the Copperband. The other issue is that although Copperbands are prone to eating Aiptasia, they don't always do it, so you may or may not get the benefit. As for pods? They really aren't pod eaters that I have heard, live
black worms is actually what most folks feed them. You also need to be very selective in which one you get because Copperbands don't ship well, so you need to ensure you are getting one of the hardier members of the species (ie one that has been at the LFS for a couple of weeks that is active and eating). An Alternative to the Copperband would be a Matted Filefish as it is more prone to eating Aiptasia and being smaller it might be less noticed by the Trigger. It's also much easier to care for: