Vibrava (the Vibration Pokemon) is a relatively rare Ground/Dragon-type Pokemon found among desert areas within the Hoenn, Unova and Kalos regions as well as the Sinnoh region on rare occasions. Generally weak by themselves, Vibrava are relatively unskilled combatants that are sorely lacking in the physical attributes that made Trapinch dangerous, instead relying on ultrasonic waves as their primary means of defense. In comparison to their pre-evolved form, Trapinch, Vibrava are completely different creatures in terms of strength and abilities, and not in a good way; when it comes to true challenges, putting up with this strange critter is one task few trainers dare to attempt!
Trapinch are among the few species of Pokemon that mutate into Dragon-types upon evolving due to an extremely rare genetic condition. However, this mutation comes with a serious cost for Trapinch because, while most of their stats go up at least slightly, they lose 30% of their base Attack stat upon evolving into Vibrava. This is because Vibrava can't develop quickly enough upon evolving from Trapinch and are thus locked in an incomplete larval stage, only reaching adulthood upon evolving into Flygon. Lacking the strong jaws of Trapinch, Vibrava are physically weaker and are less adept at close-quarters combat, making them somewhat difficult to battle with. The addition of the Dragon-type does little to help the situation, as the only Dragon-type attack that Vibrava can learn is Dragon Breath (which they obtain upon evolution).
The most important change that occurs as a result of this evolution is the addition of wings; this sort of change in of itself is not wholly surprising, as many Dragon-type Pokémon possess at least some flight capabilities. However, due to the incompleteness of their body, the wings of Vibrava are only suited for short flights; in truth, the only flight-based benefit that Vibrava receive from their wings is the Levitate ability and the power to learn the Fly HM. As a result of their current form, Vibrava do not hunt like Trapinch at all; instead, Vibrava employ their poorly designed wings as ultrasonic weapons. By vibrating their wings rapidly and violently, Vibrava are able to generate massive ultrasonic waves that can easily give humans headaches and stun most small Pokémon. While their prey is stunned, Vibrava then employ their only other means of offense, their relatively powerful acidic saliva, to melt their prey into a gooey mess that their weak mouths can easily handle. It should lastly be noted that, while the loss of their powerful jaws prevents Vibrava from learning many of the moves that Trapinch learn naturally, the addition of wings does give Vibrava the ability to learn several unique moves as well (aside from the Dragon Breath attack), including the Sonic Boom attack and the Supersonic and Screech techniques (as well as the devastating Boomburst attack if evolution is prevented for some time), that can help them survive longer and deal more damage in battle.
While they might not be very impressive in combat, Vibrava are nonetheless interesting examples of how strange evolution can truly be among Pokemon. While they might seem like the biggest joke out of all Dragon-types, these hardy creatures can still be loyal companions if you give them a chance, even if their lack of strength might make them impossible to properly battle with. Besides, you could always look at the bright side: It won't take too long for Vibrava to mature into Flygon, and for Dragon Tamers that like to experiment with abnormal Pokemon, that is certainly one species worth waiting for!