I used Curse with Duskull after he missed his Stone Edge, got 25%-6.25% off = 18.75%, then he killed me for 37.5%, then I switched in to a Sturdy Geodude and he hit me twice for 75%, and I switched into Venasaur & hit him with Leech Seed as it recovered with Full Restore. After this I just abused my 2nd Sturdy Geodude & a mixture of Potions & Super Potions to keep my health at maximum & weak Smack Downs to accelerate his use of Full Restores. Mission successful.