There are different kinds of nouns, proper nouns and common nouns. What kind of nouns are there? There are proper nouns and common nouns. How do I know which kind of noun to use?
All of those sentences are correct.
1. What kind of chocolates do you have? (Used when 'kind' means, a specific brand, genre, etc., e.g., What kind of movies do you like?)
2. What kinds of chocolate do you have? (OK, Non-count, Mass noun)
Note:
A. What kind of fish do you have?
(One type of fish, and what kind do you have?)
EX: What kind of chocolate do you have?
B. What kinds of fish do you have?
(More than one type of fish, and what kinds do you have?)
EX: What kinds of chocolate do you have?
Hopefully this helps.