Right, so apparently this happiness check is a lot more linked to the Dream World and Wi-Fi, but I have no idea how to access it, and I'd like to get an update on my progress with this 'lil guy: anyone know what to do about this?

Calling Bianca on the Xtransceiver will bring up a "check happiness" option for you there. I don't know what max happiness will sound like, but probably something extreme.

What really weird about Riolu...he evolved for me at level 15. Creepy huh?

Mine evolved at Level 19, in the Castelia Sewers. Now, my Eevee is trying to evolve on me, and he's at Level 28. But Turt has it correct. Calling Bianca on the Xtransciever is the happiness check of this game. However, I don't know what the message is for happiness sufficient enough to trigger an evolution (and remember that Riolu can't evolve at night ).

I personally suggest getting a massage. It worked wonders for my Riolu.

In Castelia City, go to the road the farthest to the west, where the gym is. Enter the building on the left, next to the vending machine. The woman with the purple hair on the first floor will offer one free massage each day.

(I like how the road doesn't have a name like the others.)

You can also invite Barbers to your Join Avenue, and they'll sell three different kinds of happiness ups. They'll also stop you from buying them if your Pokémon has reached a certain happiness value. I don't quite know what that value is right now.