Answer:
You and Me Against the World is the correct form.
Step-by-step explanation:
In a title, most conjunctions and prepositions are not capitalized. That being said, there's an easy rule to follow:
Conjunctions and prepositions with four letters or fewer are not capitalized, but all words with five letters or more must be capitalized, no matter if they are conjunctions, prepositions, verbs, nouns, etc. Therefore, even if you aren't certain what category the word falls in, all you have to do is count the letters.