I've been there a few times, as a matter of fact. Travelling there is simple enough, as long as you can afford the pass.

[...Which is not always the case, mind you.]

I have a Clefable, a Banette, a Butterfree, an Arcanine, a Meganium, a Milotic, an Arbok, a Lucario, a Dragonite, an Umbreon, a Lunatone, a Delibird, an Altaria, two Gardevoirs, a Blissey, a Gyarados, two Luxrays, a Heracross, a Houndoom and a Sandslash. It took some time, but we finally cover all the elemental types.