For your dog or other animal to be an emotional support animal they need to be friendly and non aggressive towards people.
The dog or other animal will not require any special training to be an emotional support animal but you must keep the animal under your control at all times.
To register a dog or other animal as an emotional support animal you can go to the website at this link
https://www.registermyserviceanimal.com/emotional-support-animal-requirements.html
You'll need to send a photo of the emotional support animal and pay a fee of $79.95 to register the dog as an emotional support animal
Landlords cannot charge extra for someone who has a registered support animal and airlines must allow the emotional support animal to fly free.