Eh, what is Russia in popular culture? It has winter, ushankas, balalaikas, vodka, bears, and, first of all, communists with nuclear power. I begged enough to stop focusing on them and go deeper into the Russian history instead. Yeah, some do, like in Warhammer Fantasy, but even they mostly stop on tsars, cossacks, hussars and streltsys (idk how to adapt them to English). What was before is not so famous and even does not have a common fantasy image to base something on it. And here among knyazs, bogatyrs and bears (yeah, they are forever) one can find… dragons.
But MLP already has its dragon standard, you can say (if you somehow noticed this, at first). Yeah, it has, but I decided to screw it a bit to add these guys and some much more crazy stuff. As for Ryssians it is because leaving them only with yet another bear cavalry unit would be boring, and Wikipedia does not suggest anything better from slavic mythology, focusing mostly on the various undead and minor nature spirits whom I can't imagine being massively militarized. Unless I will create sort of eastern version of the Vampire Counts, featuring also Koschey the Immoral who is the origin of the lich concept itself.
The one on the top is known as Zmey Gorynych'. The first word means simple "serpent", while the second is related to its origin, from "goret'" — "to burn", or "gora" — "mountain". So summary the creature (Zmey is a certain character) can be renamed into fiery hydra or mountain hydra, in comparison to equestrian swamp hydra who is bigger and has four heads, but lacks some limbs and fire breath.
The bottom one is an aspid. The descriptions I found said that it has two wings and two legs, a beak and also can breath fire. Though, images from Yandex.ru gave me a lot of cockatrices, which is quite funny like yet another "know the difference" picture. So this is not the final design for aspids, and I will try to make them more similar to cockatrice.
The trouble was that both of these creatures were considered absolutely evil in the mythology, especially aspid. So the first thought about their relationships with the ponies was the usual sort of "purge it mercilessly" just like other nations did. But then, yeah, the boring bears. So I went to the concept of holding against the tainted nature by any measures, and eventually Ryssians had accepted some "misguided ideas", because some collateral damage and cattle sacrifices is a viable cost for a flying flamethrower tanks on your side.