Riolu (the Emanation Pokemon) is a rare Fighting-type Pokemon found among grassy fields and mountainous terrain within the Sinnoh, Unova and Kalos regions. Though they might be unable to harness the power of aura like their evolved form, Riolu are powerful creatures that can certainly put up one heck of a fight despite their small size. Besides, if you are among the few humans alive that can actually read auras, then starting out with one of these little creatures might not be a bad choice; at least that way you'll be able to teach them instead of the other way around!
Although they are still quite young, Riolu have the innate ability to see and interpret the aura given off by life forms and will use this more often than their normal eyesight to see the world around them. In particular, Riolu are able to see the emotions given off by others in the form of aura waves which, oddly enough, actually consist of the electromagnetic waves given off by the brains of other life-forms. It is unknown exactly why Riolu have this special ability at such a young age let alone at all, but it is likely that this was originally their way of avoiding predators in the wild, something that has unfortunately not proven to be extremely successful as evident by their low population numbers in the wild. Moreover, this ability to read auras is unfortunately limited to just that; Riolu are usually unable to actually utilize their aura in any direct way, in turn severely limiting their ability to utilize any sort of special attacks naturally (in particular the Aura Sphere attack, which is iconic among Lucario). Even so, Riolu are still able to communicate to a limited degree with their auras, as the strength of their aura will increase noticeably whenever they become fearful or sad, signaling others to join them in order to cheer them up or provide extra protection.
Despite their small size and limited degree of aura control, Riolu are lithe yet powerful creatures that can function in battle and on the run for extended periods of time and have more than enough energy within them to crest three mountains and cross two canyons within a single night. This is duly reflected in their combat abilities, as their effective lack of special attacks forces them to utilize their speed and surprising physical strength to deal maximum damage at close range. Not surprisingly, this also means that Riolu have access to several moves that their evolved from, Lucario, do not, as they are more dependent upon surviving conflicts in the wild than they actually winning them; these moves include the Endure, Force Palm, Reversal, Screech, Copycat, Nasty Plot (likely a technique designed to assist them after evolution) and Final Gambit moves. These moves are quite effective at allowing Riolu to survive combat for an extended period of time before either striking back with catastrophic damage or avoiding battle altogether by any means necessary. After evolution, these creatures will become far more direct about their tactics and will become accustomed to fighting opponents head on.
Though their abilities might be limited in their current form, Riolu are cute but mighty little creatures that can put up more than just a fight against most opponents with little difficulty. You might have to get to know them fairly well and wait until daytime for them to evolve, but if you have the time and patience, they are an investment more than worth making in the long run. After all, it's not like there are a lot of creatures out there that can naturally read the auras of other organisms, a trait that you will soon find to be quite useful in battle!