>>40064930Hydreigon is shit and not only makes a mockery of the thing it's based on (a hydra) but also ruins the concept entirely. In relation to the question though, the other pseudos are also, for the most part, shit.
What does it have to compete with? Dragonite aka yellow barney? Salamence, the pseudo which looks like it's made of plastic?
Not gonna go through all of them, but out of the pseudos there's only 3 which look good. Tyranitar, Metagross and Garchomp. Hydreigon is about equal with Goo barney.
Also Hyreigon and Volcarona are the only 2 gen 5 pokemon that do well on popularity charts. The last big popularity poll did by Japan had the bottom of the dex filled with overwhelmingly more gen 5 pokemon than all other gens COMBINED. It was something hilarious like 66 gen 5 pokemon in the bottom 100 with the bottom 10 consisting of 8 gen 5 Pokemon.