In my own defence, Lucario's spot was occupied full-time by a Bibarrel until Sunnyshore City, and this is legit my first time using Lucario for lack of a better option.
>>27158065>Numel and SphealMy man you are set for the end.
Unfortunately, a stable supply of wild Pokemon in the Lv. 30-ish bracket are mostly in Dive areas around Sootopolis, which you're going to need the Mossdeep badge to do. Victory Road is the only good place for EXP grind unless you're looking for specific EVs instead. Third best area (probably the only option available to you) is the grass outside Lilycove but it's at Lv. 25-ish, so the going will be slow.