Houndoom (the Dark Pokémon) is a relatively rare Dark/Fire-type Pokémon found among forests within the Kanto, Sinnoh and Kalos regions as well as the Unova region on rare occasions. Dangerous to approach on even the fairest of days, Houndoom are menacing beasts that will gladly burn and devour anything foolish enough to stand in their way. They certainly might not be made to take much in the way of physical punishment, but the last thing you'll ever want is to go toe-to-toe with one of these beasts without plenty of protection against fire; don't expect any Burn Heals or berries to make much of a difference after these hounds are through, because if you ever get burned by them, you might as well consider it a permanent scar!
Upon evolving into Houndoom, these creatures finally gain access to their full array of Dark and Fire-type attacks (as well as the ability to learn the Thunder Fang attack with some practice) and instantly become devastating contenders on any battlefield. Aside from being able to strike with powerful moves like Crunch and Foul Play, Houndoom are particularly noted for their devastating Fire-type attacks and, perhaps more importantly, their distinctive 'toxic flame'. Like Houndour, Houndoom allow the toxic gases that build up from failed combustion to sit in their mouths in order to give them a slightly septic bite, but their manipulation of these toxins goes far beyond what their pre-evolved form could ever hope to accomplish. Instead of merely spewing out the rancid smoke that comes from their incomplete combustion, Houndoom inhale the gas back into their combustion chamber and allow it to sit there until needed; when Houndoom become exceptionally angry, they channel their frustration into then churning this gas and infusing it into the walls of their combustion chamber in such a way as to transfer the toxins present in the smoke directly into their flames, in turn making them the only Fire-type Pokémon able to naturally spew poisonous fire. In most cases, this does nothing if it strikes an armored enemy; if the flames actually come into contact with soft flesh and leave a burn, however, the toxins in the flame will be infused directly into the singed flesh and will remain there even after the skin heals, constantly inflicting terrible pain until death in some cases. Only the immediate and complete removal of singed flesh can prevent this sort of permanent pain from being inflicted.
As with Houndour, Houndoom are natural pack animals and are effectively unmatched in terms of coordination abilities because their cries are delivered at abnormal frequencies that are indecipherable to creatures outside of their own family. Moreover, the cries and howls of Houndoom are often considered to be among the most frightening of things one can hear at any time of the day, as it is almost a sure sign that a pack of these beasts will soon appear to ravage any prey they can get their teeth on; not surprisingly, this has led many people to see their 'evil' cries as a signal from the Grim Reaper himself. Since they are effectively adults and no longer have to worry so much about limited combat abilities, Houndoom often times bicker amongst themselves and actively fight for both entertainment purposes and for mating rights. The most highly-valued purpose of fighting among the species, however, is actually for the title of pack leader. Houndoom take great pride in their abilities and will sacrifice everything they have for the title of pack leader, as it not only allows them to lay claim to food reserves before anyone else but it grants them the same rights during mating season. While it usually doesn't do trainers much good when confronted with multiple Houndoom in the wild, it is fairly easy to tell which Houndoom is the pack leader as their horns will be raked back far more shapely than the others (it is believed that this is due to hormone changes that occur after they apparently become pack leader, though a full anatomical explanation has yet to be created). If the pack leader is taken out before any of the others, the chances of the remaining Houndoom stopping what they were doing and initiating fights with one another is quite high, but doing so is also at the risk of facing tremendous retribution from the remaining members as well. Overall, Houndoom are extremely dangerous to approach in the wild and should be avoided at all costs regardless of a trainer's skill.
It is lastly noted that Houndoom is one of only 46 species of Pokémon known to be capable of undergoing Mega Evolution. Tightly holding on to a Houndoominite, Mega Evolution radically changes Houndoom by forcing the growth of massive, bony extensions of their skeleton across their chest area and along their spine as well as considerable growth in their horns and a significant upward twist to their growth direction. The bony material now protruding from these beasts’ body is thicker than the rest of their bones and more than capable of resisting direct attack from just about any type of move, especially in regards to physical attacks. Despite the extra weight that this gives to Mega Houndoom, their muscles are also more well-developed in this form so they are more than capable of pulling the extra mass with little problem; moreover, they are able to make much more efficient use of their internal flame sac to scorch opponents in battle and tend to be a bit more ferocious than they already are initially. In terms of stats, this mutation within Mega Houndoom slightly increases their base Special Defense stat, moderately increases their base Speed stat, considerably increases their base Special Attack stat and critically increases their base Defense stat; in turn, Mega Houndoom gain the highest base Special Attack stat out of all non-legendary Dark-type Pokémon. In addition, the new outgrowth of bone material is different from the rest of the beast’s skeleton in that it can absorb and convert thermal energy it picks up from the heat of sunlight, granting these beasts the Solar Power Ability and in turn making them a dangerous beast to approach both at night and in the middle of an otherwise sunny, pleasant day.
Despite their lack of physical durability, Houndoom are vicious canines that can more than just sink their teeth into any opponent that dares to underestimate their vigor in battle. With impressive intelligence and a poisonous flame that all but the most heavily-armored of opponents fear, Houndoom are certainly the worst enemies you want to face without some serious type advantages on your side. Do yourself a favor and try not to fight with one of these beasts without giving them a cocktail of chemicals to neutralize their toxins; otherwise, you might find yourself paying for a few unnecessary hospital bills just because some trainer is foolish enough to fight with an unarmored Pokémon!