my azurill is lvl 18 and unevolved so I want to know how I can find out its happiness rating and also what are some ways to raise a Pokemons happiness in white 2?
In Black/White 2, you can call Bianca via Xtransceiver to see how happy a Pokemon is. Her answer gives an indication of the happiness level.
For context, most species start with 70 happiness (exceptions) and evolution requires 220. There is also a friendship rater in Icirrus City, but they function the same as Bianca, who is way more convenient.
See this table on Bulbapedia for ways to raise happiness. Overall tips: