For example, let's say I have a pair of Mew and want to teach them moves that when in a double battle they will cover every type that comes against them but seeing as how it is only 2 pokemon i can only have 8 different types of moves so therefore i need move types that are super-effective against at least 2 types. If this question is confusing feel free to ask for more elaboration. Thanks in advance. -Okami