You know, there might be a lower-tier Dragon type like Altaria, or Druddigon, but I'll be honest, Dratini and Bagon are not gonna be in any time soon, and when they are, they're not gonna be easy to find.
I'm doing this for a couple of reasons.
Firstly, the Black and White Pokemon games set a new precedent in including Pokemon that evolve at higher levels- so that even when you catch them late-game, you still have to train them a bit to evolve. This is actually a great improvement from previous generation's patterns, wherein you would often be given Pokemon lategame that you could just level up once and evolve them without really "getting to know them". Accordingly, I'm choosing species somewhat based on the levels they evolve at (hence the rush of Bug Pokemon that are available early). For the same reason, many 5th gen Pokemon will not be seen until much later in Reborn.
Secondly, we're all coming from a competitive battling site, and unlike the average Pokemon player, we know what's good and what's not. I'm deliberately holding off on including many OU pokemon until much later in the game (with some exceptions a la ninetales/alakazam) because at that point they require more effort to train up to the standard level. I can also do more with sidequests at those points to make them harder to obtain. i.e I'm roughly trying to balance the work it takes to get them with the reward the player will get from having them.
Throwing in a Dratini at this stage of the game, and letting Trainers have it through the whole time is actually going to discourage them from exploring other options. By that I mean, there are a lot of Pokemon that I get the feeling people don't necessarily want, but since they don't know when they'll be able to get anything else, or if they will, they end up using them and broadening their horizons. Now if you're operating on a six pokemon party and constantly swapping out the things you have for things you find and like a little bit more, then as a player you end up catching and training a wide variety of Pokemon and having what I consider to be a pretty fulfilling game experience. On the other hand if you're able to get all the things you like best right at the start, you're probably just going to get those things and never bother with anything else ever- not such a broad experience. If I give something like Dratini away, most players are going to jump at that chance and not consider using other things. I'm already seeing this with Abra and regretting including it so early, but.. Anyway.
Those Pokemon will be in, but not for a while. Sorry. D: