The Swinub line, as well as Delibird, are also available early in the Wild Area if it's hailing. I can confirm that as the very first area was hailing when I got there first :PThere's almost everything available by that point. The only typing you'd lack in variety is Ice, as the route-only ice types are after gym 5, and in wild area you can only run in Avalugg, Vanillite and Obamasnow families.
Well, there's also quite a scarcity of dragons, I'm unsure if you can even run into any at all aside Axews and Trapinch.
I didn't find wild Bergmite though, until Route 9.
Also, there are wild Applin in Route 5, and wild Noibat near the ruins in the Wild Area (though I'm not sure if they can be caught as soon as you get there as the ghosts there are above level 20)