What I've put together thus far for these found in Kalimdor.

Horde Homelands

Kalimdor Battle Pet Tamers

Zunta – Level 2 – Durotar

Beast, Critter USE Mechanical, Beast

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Dagra the Fierce – Level 3 – Northern Barrens

2 Beast, Critter USE 2 Mechanical, Beast

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Analynn– Level 5 – Ashenvale

Aquatic, Critter, Flying USE Flying, Beast, Magic

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Zanya the Sadist – Level 7 – Stonetalon Mountains

2 Beasts, Critter USE 2 Mechanical, Beast

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Merda Stronghoof – Level 9 – Desolace

Aquatic, Critter, Elemental USE Flying, Beast, Aquatic

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Cassandra Kaboom – Level 11 – Southern Barrens

3 Mechanicals USE 3 Beasts