What's a good dog breed to pair up with a beagle?

Your mom

a newfoundland

Boxer....not necessarily because it will be a good pair, but because they are the most amazing dogs out there. He will also get along great with your other dog though.

lab mix from the pound

I've had my female beagle paired with a Fox Terrier from the ages of 5-8 then when she got about 15yo I paired her with a shih Tzu pup. She was/is best buds with both dogs.

a rabbit

My dad has a blue heeler/beagle mix. If you google that mix, you'll easily see what it will look like.

I've got a beagle mutt that is either bluetick or blue heeler based on the coloring.

Doesn't bark like a beagle but has an easy going disposition which makes me think bluetick. But can jump about 6 feet straight up so I think blue heeler.

American Bulldog