The Unova region features many Dragon type Pokemon, and the second evolutionary set from this region features Deino, Zweilous, and Hydreigon. These Pokemon are also some of the more difficult to evolve in the fifth generation due to high evolution level requirements. However, they have become favorites among fans and Hydreigon will even be featured in the upcoming movies.
Since only Deino is the only one of the three available in the game through regular play and is very rare, finding just one may take a good amount of time. It can only be found within the caves of Victory Road around level 40. However, the capture rate for this Pokemon is fairly high, so it should not be difficult to catch.
Due to the Hustle ability of both Deino and Zweilous, using one in battle will be a little difficult since the accuracy of any move is only 80% of its normal accuracy. Once Zweilous evolves into Hydreigon at level 64, its ability becomes Levitate, which is very useful. Hydreigon will not take damage from Ground-type attacks or spikes, so it can be sent out under situations where most other Pokemon would be damaged or poisoned.
Deino and Zweilous both benefit from knowing physical attacks, and the moves they can learn through leveling up work well with their relatively high attack stats. Crunch and Dragon Rush would be good choices, though you may want to attach an item to these Pokemon to improve their accuracy.
Hydreigon is different from the other two as its special attack is now higher than its regular attack stat. Many TMs and attacks it can learn take advantage of the higher special attack. Flash Cannon or Flamethrower are both viable TM options, while Dragon Pulse and Hyper Voice from leveling up should also be considered. If you need a Pokemon who can learn HM attacks, this Pokemon can learn Fly, Surf, and Strength, which are some of the stronger and more useful HMs. With egg moves it is also possible for all of these characters to learn the three elemental fangs Fire Fang, Thunder Fang, and Ice Fang.
In the video games, Ghetsis is the only trainer to own a Hydreigon, and it is one of the strongest Pokemon in his team. Defeating it will require some strategy, strong Pokemon, and quite a bit of luck.
Hydreigon will make its first full appearance in the anime with the two newest movies featuring Victini and the two legendary dragons. As the air date of the movies near, many products featuring this Pokemon will also be available, such as plush and the zukan figure. Thus far, none of these three Pokemon have been in the anime, so Hydreigon will also be the first of the evolutionary set to be featured in an episode or movie.
With Deino being the only one of the three available in the wild, it is the only one that can be obtained as a shiny through random encounters. Through Masuda Method breeding, it is also possible, and more likely, to also obtain a shiny Deino. Both a shiny Zweilous and Hydreigon have to be obtained through leveling up and evolving a shiny Deino.
Hydreigon is incredibly strong, and is a great Pokemon to use in a team after the main story line. However, you will have to have a bit of patience if you try to get one starting at Deino, as it may take a while to evolve. All the effort will be worthwhile as it will take a long time to faint a Hydreigon when it starts out at full health.