My idiot brother decided to swap wiimotes with someone for kicks, long story short a return swap is not possible. So we're trying to figure out how to reassign the new wiimote with the wii. Anyone know how?

Go to the remote settings option, and click Reconnect. Then just hold down the 1 and 2 buttons of the new remote

Thank you kindly.

If that doesn't work, when you turn the wii on and it gets to the safety/warning/health screen, pop open both the back of the wiimote and the latch at the front of the wii and press the red button on both (I think you press the wii one first but I'll admit, I don't remember...if it's not working then first press the wii remote red button and then the wii red button).

Don't sweat it, all is right with the world.

Izaaz's method will permenantly reassign them to the Wii.  Radishhead's method will assign the remotes as 'guests' to the Wii and may not stay connected after full shut down.