So, I was playing through Emerald lately, and long story short, Roxanne's Nosepass had swept all of my team except for my Level 7 Nincada. Nosepass had already gotten up to max defense with Harden. I had Nincada use Leech Life, in hopes of stalling and recovering, but for some reason, when I used it, the game didn't say "It's not very effective," even though it should be because Rock resists Bug. I couldn't tell if it was still doing resisted damage, since I was only doing 1 HP per hit, but still, what's up with that?