There are a number of battle/companion pets in the pet journal in Cataclysm Classic that are not currently showing up in the MoP Beta pet journal. Most were promotions or in-game shop pets that were available only on Classic clients.
I would be curious to know if these pets will carry over into MoP Classic as battle pets or companions.
That one is not classic-only. You can get it from a Cataclysm achievement, even in retail.
Its dumb but there are more than 1 pebble pets. The 1 they are referencing was from purchasing the Northrend Heroic / Epic upgrades and its a penguin (I’m not sure if it made its way to a standalone purchase in classic). The pebble from the achievement is a rock elemental. Retail has Mr. Chilly, pengu, and tundra penguin. I’m fairly certain the pebble penguin isn’t available in retail.
Unfortunate naming then
There are two Pebble pets. This one is Pebble the Penguin and is, as far as I’m aware, a Classic-only pet.