I did some damage calculations and, by god was I both shocked and happy. Shocked that my Rhyhorn's Rock Slide won't OHKO an EV-less, lower level Gengar... And happy I didn't go ahead and fight Morty prior to my last save, since Shadow Ball cleanly 2HKOs. Combined with the fact I'm likely to take a Curse prior to Gengar gettin' sent out, means that my challenge would of ended early.
So instead of losing miserably to that damned ghost, I went off towards Olivine and through the Olivine Lighthouse and fought every trainer possible to level grind. I shortly returned to Ecruteak to take on Morty afterwards.
His Pokes prior to Gengar did little to stop me; Rock Slide OHKO'd, and I didn't miss once. His Ghastly got a lucky paralyze on the Lick, and his first Haunter did a pointless Mean Look. Strangely, he decided to send out Gengar before his second Haunter. Even more strangely, he did Sucker Punch instead of Shadow Ball, doing laughable damage and ensuring only the most ridiculous amount of hax could stop me now, as Rock Slide is an OHKO after the level grinding.
His last Haunter easily falls as it uses curse in all due futility. Rhyhorn comes out on top once more. Fog Badge get!
Traveled back to Olivine, crossed the sea (and level grinded against all the trainers, of course! Rhyhorn still ain't that over-leveled), and survived a crit from a Krabby's Bubblebeam. Had a heart attack when I saw Rhyhorn's 100% health plummeting by 70%... >_>;
Saved in front of Chuck's gym. Rhyhorn's rock-hard body is ready. Don't think I ever did a full summary for Rhyhorn, so here it is for once.
Rhyhorn @ Everstone: lv. 37
Ability: Rock Head
Take Down (**** you Rock Blast, thought ya had 90% accuracy, not 80%...)