>>34759073Duskull is available on Route 209 and Lost Tower in all fairness. The dex sucks though. Many of the Pokemon in the Sinnoh dex are nearly impossible to reliably get because of Honey tree or Great Marsh bullshit, plus Feebas in Mt Coronet. There's rare, then there's just so rare that there's no point even bothering. There's a reason every DP team was starter/Staraptor/Luxray/Water type/Garchomp/Bronzong or something else. Little else was worth trying to get as many of the available Sinnoh mons were either too rare, too late, sucked, or all three.
I agree on the Zubat and Geodude problem, it's worse here than anything past Johto. Gamefreak has constantly relied on the same mons being common in almost every game. Zubat, Geodude, Tentacool, Rattata, Wingull and Pelipper, Magikarp. Zubat is fucking everywhere in Alola and after 20+ years it shouldn't have to be this way anymore.