I hate Rayquaza.
To me, it's a very lazy design in terms of typing. It's dragon/flyjng, and normally I'd be thrilled about a Pokemon receiving a never before used type combination. But the Rayquaza line is just a flying snake who's arbitrarily humanoid. Other flying types derive their secondary typing from the species they're based off of. Pidgey is flying type because it's a bird. Hoothoot is a flying type because it's a bird. Rayquaza, rather than being something tangentially related to dragon like a biscuit or a horse, is just a forcedly humanoid flying snake. The connection is forced, inorganic and the result of just making an animal anthropomorphic with no justification.