No, "counterpets" generally means a companion that is strong against a specific family while that family type's attacks are weak against it.
A basic example would be a dragonkin pet with magic attacks up against a flying companion. The opponents attacks towards the dragonkin would be weak, and at the same time the dragonkin's attacks towards the flying pet would be strong. Ultimately, the dragonkin companion would have the advantage in the battle.
So far the community has found at least one example of a counterpet for each pet type:
*Aquatic: Jade Owl (magic with flying attacks)*Obviously, these aren't hard and fast rules, but these seem to be the best counters for each family type so far.
Beast: ?? (none atm, but ideally flying with mechanical attacks)
Critter: Flayer Youngling (humanoid with beast attacks)
Dragonkin: Scourged Whelpling (undead with humanoid attacks)
*Elemental: Any snail (critter with an aquatic attack)*
Flying: Sprite Darter Hatchling (dragonkin with magic attacks)
*Humanoid: Any spider or maggot (beast with an undead attack)*
*Magic: Mechanical Pandaren Dragonling (mechanical with a dragonkin attack)*
Mechanical: Any elemental with elemental attacks will work
Undead: Any frog or toad (aquatic with critter attacks)
Keep in mind that the ones marked with an asterix aren't absolutely ideal since they might not come in the highest quality (Jade Owl and Mechanical Pandaren Dragonling) or they may only have one strong attack. The quality issue can be addressed once Battle-Stones are released in 5.1.
Some other possible counterpets in the next major content patch:
Flying: Nexus Whelpling, ChrominiusThe Corefire Imp was another candidate, but it only has one attack that would strong against critters. The two mentioned above have at least two strong attacks.
Critter: Kun-Lai Runt, Stunted Yeti