Correct question: Whose loyal friend is Captain Sniff, who helps rescue people?
Or as a statement: Captain Sniff is a loyal friend who helps rescue people.
Why this is better (easy explanation):
- The word "whose" asks who something belongs to, for example: "Whose toy is this?" To ask that about Captain Sniff we need the verb "is." So we say: "Whose loyal friend is Captain Sniff?"
- We add "who helps rescue people" to tell more about Captain Sniff. That part is called a clause and it describes him.
More simple examples:
- Question: "Whose dog is Buddy?"
- Statement: "Buddy is a dog who helps rescue people."
If you want, you can tell me what you meant and I will help make the sentence exactly how you want it.