Holy shit, nobody in this thread has any fucking clue what they're saying.
Special Lucario became viable as soon as it got Nasty Plot. It's considered a good alternative to physical Lucario because 1.) Everyone EXPECTS physical Lucario, and 2.) Dark and Fighting give perfect Neutral coverage unlike what this fucker is saying
>>12411075 , and with having Vaccuum wave as a good niche priority move.
Vaccuum Wave, despite what
>>12411152 is saying, is actually really good. Terrakion, Scarf-Heatran, Hydreigon, Kyurem-B, Scarf-Magnezone, Mamoswine, Jirachi and Scizor all become less of a headache.
The trade-off is that now fast flying types become an issue, and need more softening before Lucario can come in. Landorus, Thundurus, Salamence, along with Lati@s and Gengar. Granted, Gengar is a problem regardless.
There's also the bonus that you're not vulnerable to Burns, and that you tear sand teams apart harder. Lucario is a pokemon that systematically tears apart teams as long as it has the right team support and a brief instant to set up.. the special set just deals with things differently, usually by giving you a higher chance of BEING able to set up.