The three babies are all level one and all know Double Team, Confusion, Teleport, and Lucky Chant.
Ralts baby #1:
Female, Naive, Alert to sounds
Synchronize
Ralts baby #2:
Female, Lax, Proud of its power
Synchronize
Ralts baby #3:
Male, Relaxed, Likes to relax
Synchronize
Do any of those sound good?
I just checked, and both parents have Synchronize as the ability. Ugh. I would rather have Trace.
First of all, yeah, Trace would definitely be better as an ability. The moves could use improvement for sure but that's not an issue since you can, and undoubtedly will, change them.
To be honest, the nature really depends on which Pokemon you tend to evolve it into (as does the gender, obviously). If you want to evolve it into Gallade you need a male. Also, Gallade excels in Attack whilst Gardevoir excels in Special Attack. If you do a pure Physical/Special set for Gallade/Gardevoir, respectively, then Adamant/Modest is good, respectively.
If you want to do a mixed set, Lonely or Naughty might be good for Gallade, Mild and Rash might be good for Gardevoir. Ideally though, you'd have sets purely Physical or Special and have Adamant or Modest.
Speed raising abilities wouldn't be bad either...I mean, I suppose Naive could work. Lax isn't good unless you intend to make them defensive, which they're not really suited for (plus, in the main story you don't tend to get a whole lot of benefit from anything but just attacking, I find). Same goes for Relaxed.
Again, ideally you'd try to get one of the other natures. If you really don't want to breed more, Naive is your best bet.
Is the rest a good team? I just got rid of Kadabra because it was annoying me. And it was traded, so it likes to disobey.
Togetic
and Staravia is type redundant, although there are a lot of bug and grass Pokemon in Sinnoh, from my experience, so it wouldn't be a huge problem. To be honest, you could probably keep them both and be fine. Other than that, it seems to be pretty balanced to me thus far.
Plus, is it possible to get Houndour this early in the game?
Yes, it is. Directly south of Veilstone, in fact, is a route on which you can catch Houndour. You can also catch them at the Valor Lakefront. (I think the other guys are thinking of D/P -- Houndour's in the Sinnoh Dex in Platinum.)
And how do you get Togetic/Togekiss to learn Sky Attack? Do you have to breed it with a Ditto?
Um...I'm not really sure on this one. Looking at its Pokedex entry, it says Togekiss starts out with it but it isn't listed anywhere else.