Starting Pet battles, have large amount of leveling stones.

[Shadow Fox]

I've been working on leveling my Onyxian Whelpling. Got it to 20, and I have a ton of Leveling stones I can use to power level another pet... Kinda curious what would be another good pet to boost that synergizes well?

I've read around a bit (While may be outdated) that Gilnean Raven is a solid choice?

Not really big on pet collecting or doing the challenges yet so I don't have any of the absolute-must-haves or really rare pets: Trying to get a starting group of 3 before I do that are well balanced?

[Abutabah]

Anubisath idol is a pet used in a lot of the tamer fights around azeroth. Would be a good choice to level.

[XanderGryphon]

http://www.wow-petguide.com/index.php?m=LegionChecker can be a pretty good tool for getting started

[Yoshimiko]

Anubisath Idol is the #1 pet to level to 25. Once that pet reaches 25, you can easily and quickly level other pets via MoP dailies.

As for the rest of your lil guys:

Unborn Val'kyr is level 23 when you catch it - it's a short hop to 25, and I use this lil guy everywhere. I probably use it the most of any of my pets.

Teroclaw hatchling is an incredibly tanky pet. I regularly consider it one of the best PVP pets in the game. It mixes with the Val'kyr very well - Doom/Haunt + dodge & regen. Nasty combo.

Raptor pet with "swarm"-like ability(Falcosaur Swarm!, for example) is the new version of howl bomb. The 4 raptor pets that came with 7.1 all have level 25 quests and ultimately end in a mount each. A good choice to get to 25.

A rabbit with Burrow, Dodge and a speed/speed nature is always very good. There are a lot of options. Just make sure you can see their nature. Requires very little leveling, as you can catch them at 25(which reduces to 23). Arctic Hare is my bunny of choice.

Darkmoon Zeppelin is solid. Lil' Bling shows up on a lot of lists. Xu-fu is the only pet worth using from the tournament, imo. Magical Crawdad if ya got 'em. I've heard people claim Hyjal Wisp is one of, if not the, best pve pet. Pets with Ghostly Bite(like Frostwolf Ghostpup) are incredibly potent, especially if they're power/power. Harbinger of Flames is very good for boss killing, especially when teamed up with 2x Mindslayers. Rapana Whelk is a critter with drain - amazing combo. Pandaren Water spirit for a disgustingly powerful combo.

I think that covers all pets you could *need*.

With whelpling, I'd focus on Anubisath Idol next. After that, Snag yourself a speed/speed bunny - you can just grab a variety of them that are already level 25(reduced to 23) and it's a short hop to 25. Grab a Rhapana Whelk and moth - then you can power level the rest to 25 on MoP dailies.

[Stormcall]

Anubisath Idol is the #1 pet to level to 25. Once that pet reaches 25, you can easily and quickly level other pets via MoP dailies.

As for the rest of your lil guys:

Unborn Val'kyr is level 23 when you catch it - it's a short hop to 25, and I use this lil guy everywhere. I probably use it the most of any of my pets.

Teroclaw hatchling is an incredibly tanky pet. I regularly consider it one of the best PVP pets in the game. It mixes with the Val'kyr very well - Doom/Haunt + dodge & regen. Nasty combo.

Raptor pet with "swarm"-like ability(Falcosaur Swarm!, for example) is the new version of howl bomb. The 4 raptor pets that came with 7.1 all have level 25 quests and ultimately end in a mount each. A good choice to get to 25.

A rabbit with Burrow, Dodge and a speed/speed nature is always very good. There are a lot of options. Just make sure you can see their nature. Requires very little leveling, as you can catch them at 25(which reduces to 23). Arctic Hare is my bunny of choice.

Darkmoon Zeppelin is solid. Lil' Bling shows up on a lot of lists. Xu-fu is the only pet worth using from the tournament, imo. Magical Crawdad if ya got 'em. I've heard people claim Hyjal Wisp is one of, if not the, best pve pet. Pets with Ghostly Bite(like Frostwolf Ghostpup) are incredibly potent, especially if they're power/power. Harbinger of Flames is very good for boss killing, especially when teamed up with 2x Mindslayers. Rapana Whelk is a critter with drain - amazing combo. Pandaren Water spirit for a disgustingly powerful combo.

I think that covers all pets you could *need*.

With whelpling, I'd focus on Anubisath Idol next. After that, Snag yourself a speed/speed bunny - you can just grab a variety of them that are already level 25(reduced to 23) and it's a short hop to 25. Grab a Rhapana Whelk and moth - then you can power level the rest to 25 on MoP dailies.

I'll add a couple more good options:Mechanical Pandaren Dragonling, Nexus Whelpling, Zandalari Anklerender, and a water strider of some kind.

[Vargur]

Son of Animus, Son of Sethe, something with Life Exchange (install Rematch addon and search for that spell).

[AndaliteBandit]

Don't forget about Terrible Turnip!

He's ideal for capturing wild pets without accidentally killing them. That's harder than you'd think sometimes.

[Hawg]

Don't forget about Terrible Turnip!

He's ideal for capturing wild pets without accidentally killing them. That's harder than you'd think sometimes.

Terrible Turnip's days of mandatoryness are over my friend The new corgi's and Grumpy all have the ability Super Bark which does the same thing.

[Splenda]

Terrible Turnip's days of mandatoryness are over my friend The new corgi's and Grumpy all have the ability Super Bark which does the same thing.

I actually didn't know that, these are two I haven't leveled, so neat! I agree with the general idea, I would pick one of these to level for how damn helpful that ability is.

[Hawg]

I actually didn't know that, these are two I haven't leveled, so neat! I agree with the general idea, I would pick one of these to level for how damn helpful that ability is.

You do still need to be careful if there anre any buffs up that do extra damage, they can cause those abilities to kill the capture pet.

[Sol77]

Anubisath Idol (AQ or AH) can solo several tamers, allowing you to carry two lvl1 pets in the same fight. So that's what you want first.

Then just get good pets of each other family.

[AndaliteBandit]

Terrible Turnip's days of mandatoryness are over my friend The new corgi's and Grumpy all have the ability Super Bark which does the same thing.

Those are definitely helpful as alternatives, but Weakening Blow is convenient because it doesn't have a four round cooldown.

[netherflame]

Graves from HoTS is a really solid pet too, but you have to play HoTS to a certain point to get it.