Pokemon RPG in Ruby

Is there a more efficient way to do this? In terms of lines of code that is; I really don't want to have to do a fuck ton of case when case when shits again....

http://pastebin.com/gdTevCRJ

>>6
That would be even longer, since you'd have to do every type for every other type, whereas there are only modifiers for a few combinations in the pastebin.