There's Canine Freestyle and then there is Canine FreeSTYLE!
Most teams that perform tend to dress up along with their theme. This isn't completely necessary but does add to the performance.
Things to keep in mind:
Dressing up your dog can be great and adorable but would you risk style for safety? I personally only put dog related gear on my pups. Such as harnesses or bananas and like Simon Cowell said " The reason America Loves Hero is because he looks like a dog "
Make sure you wear something that allows you to be able to move freely in. You don't want to have anything restricting or to revealing.
For the dogs and for the humans costume, you want to make sure you have a breathable, comfortable fabric that wont easily rip.
Below are some examples of dos and don'ts