Well, as once again you've asked for my opinion, here we go!
Abandoned by their parents at birth, Alexa (a Shinx kitten) and Axos (Houndour pup) are taken in by a lone Luxray queen. As the pair mature, it is their unlikely alliance that will forge a friendship between Houndoom and Luxray forever.
If so;, you'll have to show this to us (otherwise we'd have to guess). Another thought is then, if there are differences between the two (similar to, as another said, Romeo and Juliet), how fierce is the rivalry between them, and why the 'Luxray queen' (curiously, is there such a thing as a 'head lioness'? I wouldn't know, so hopefully you've had a look at such things and already sorted them out, made sure they made sense and all) would take in the Houndoom in the first place. Wouldn't the other Luxray then disagree? And so forth.
Also - why are they both abandoned by their parents at birth? It's an odd thing to happen, for starters, and givent hat Houndour/Houndoom apparently hunt and hence live in packs, that means that the Houndour somehow got separated bythe pack, or has no pack to go to. That's another thing that occured to me as well, so keep that in mind, so it isn't left unexplained.
There's a few open areas here already (which I suppose is only natural given how brief the summery is...), so be sure to think them out carefully and all. Otherwise, it is kinda hard to judge so far, as there's not too much to go on.
And as with all writing, show, don't tell, yadda yadd yadda, and good luck with it, if you follow through with your idea.