Dunamis (PREMIUM)
The Dunamis pet is the best available for all warriors, though it favors pure builds due to the fact that it uses your STR stat rather than your CHA. Rather than damaging the monster, Dunamis instead boosts the player's melee damage by 24.7%
Location: 20000 Z-Token package
Thernda (PREMIUM)
Thernda works the same way as Dunamis does, except it boosts ranged damage and uses the player's DEX as its source of 'damage'. Ranged weapon attacks get a boost of 24.7%, and ranged SP skills get half the boost: 12.4%. It's definitely worth noting however, that FD rangers should not use Thernda at all. Thernda in its base state is inferior to elemental pets, but as it derives most of its 'damage' from the player's boosts, such as misc items and the Chieftain's IronThorn shield , it ends up being greater when used with FO armors. Since FD rangers don't use the same boosts, they're much better off using normal pets.
Location: 20000 Z-Token package
Poelala
The Poelala pet is a must-have for all mages. As it derives its 'damage' from INT rather than CHA it does favor pure mages, but it's definitely very useful for Beastmasters too. I put the term 'damage' in quotation marks, because while it doesn't damage the monster at all, it instead boosts your magic weapon damage by 32.9%, and your spell damage by 12.4%.
Location: Valencia -> Golden Giftboxes -> UltraRare Shop
ChickenCow Clone (SEASONAL)
This is a great utility option for Beastmaster builds that returns every year during the February Golden Giftboxes event. It follows the type and element of your weapon, so you could cover all 8 elements + Harm in one pet slot using ChickenCow Clone. However, it has a -15% damage penalty, and you take more damage as well.
Location: Valencia -> Golden Giftboxes -> UltraRare Shop
Keyote (RARE)
Keyote used to be available from the Void Challenge, but is now permanently rare. If you have it however, then this is the best option. You can click on its staff to swap between two attacks: a strong 4-hit attack that deals 5% more damage than normal, and a 2-hit attack which can paralyze the monster, though it only deals half the damage to compensate.
Location: None
Flareos (PREMIUM)
Flareos is the best option next to Keyote, and it's still available albeit premium. It comes with 2 attacks: a strong, 2-hit ranged fire attack with a +5 BTH lean, and an attack which does no damage, but has a very high chance of Controlling the monster. You can click on him to swap between the two attacks.
Location: 12000 Z-Token package
Rose-in-Full-Bloom (SEASONAL)
The best option, bar none, for beastrangers since it complements the Sol Neko armors so well. Like many other pets on here it has a toggle between two different attacks. The first is a simple pure damage attack with a +3 BTH lean and a +4.25% damage MC bonus, nothing to write home about. The second hit however deals 50% damage, but can burn the monster if it connects - on top of that, the monster is also inflicted with Berserk, causing its BTH to be lowered by 20 for two rounds.
Location: Snugglefest -> 2008
Underwyrmling
Has a toggle between two modes: the first is a pure damage attack, two hits. The second is a 3-hit attack that damages the monster's SP.
Location: Travel Map -> Sail East -> Mt. Thrall -> Hollow's Garage -> Underworld Saga -> Escape the Wicked King (Challenge Mode)
Floating Pie
A solid option, though outclassed by the likes of Flareos and Keyote for obvious reasons. It comes with 2 attacks and you can toggle between them by clicking on it. The first is a standard 2-hit attack that deals 5% more damage, and the second is a 4-hit attack that can paralyze the monster - however, the monster is also healed for half the damage dealt.
Location: Warlic's Shop -> Mastercraft Sets -> Dessert Set
Mini Nulgath
This is a good option for those who need compression. It's a standard pure-damage pet with a 2-hit attack, that seeks between fire and darkness.
Location: Valencia -> Golden Giftboxes -> Rare Shop
FruitcakeZard (RARE)
This is the best water pet in the game, period. However, it's permanently rare as it was only available during Frostval 2015. It has two attacks: one which gains 5% more damage, and another which can paralyze the monster at the cost of 50% damage. By clicking on the pet, you can switch between the two.
Location: None
Emodjinn (SEASONAL)
Emodjinn is the best option below FruitcakeZard, and it returns every year on April 1st. Its attack can Daze the monster, for a 16.8% chance of not acting during the turn. However, it has a -20% damage penalty to compensate. If the monster is already dazed, then the pet will instead use a purely-damaging attack.
Location: April Fools -> 2016
Badb Catha
If you're waiting for April 1st, then this is the best water pet available. Its attack consists of one ranged water hit, and if it connects then it can Control the monster.
Location: Warlic's Shop -> Mastercraft Sets -> Celtic Set
Psychedelic Dinosaur (RARE)
While it's permanently rare, there is no better option if you already have it.
Location: None
Dire Wolf (RARE)
A nice pure damage option, though it's no longer available. It's part of the Windter Warrior set, from the 2016 Frostval Giftboxes.
Location: None
Experimental Robocockatrice (Z-TOKEN)
An amazing option for wind, if you can afford the tokens. Its first attack deals a small amount of earth damage, but can Petrify the monster, making them unable to act for the turn, and changing their wind resistance to <earth res x 1.5>. If the monster is already Petrified, then the pet will perform a powerful 1-hit wind attack.
Location: Miss Fixit -> Who's Kamui?
Fujin's Curse
The best non-rare, F2P option. Its attack consists of 3 equally powerful hits, and if they all connect, then it can lower the monster's blocking chances for wind damage for the turn.
Location: Bridge to the Sky
Nerfkitten
Each attack reduces monster MRM and increases its own damage. Caps at +10% damage and +8.5 BTH. CHA v LUKm LUK v INT +0 save.
Location: Guardian Tower -> Guardian Shop
Info Links: http://forums2.battleon.com/f/tm.asp?m=7043761
Nilak
MC is +20 Freeze Potence (makes Freeze easier to inflict). Non-guardian characters can use it but not buy it from the shop so you may use the vault to transfer it to adventurer characters.
Location: Guardian Tower -> Guardian Shop
Info Links: http://forums2.battleon.com/f/tm.asp?m=22316992
Ice Cream Golem
Click to toggle between Daze mode and damage mode, Daze mode the pet gives up 55% damage to attempt an 18.49% stun rate Daze that lasts X turns, X being the hits that connected, max 2. 50% save, player CHA/LUK vs mob END/LUK. In damage mode it deals 105% damage.
Location: Warlic's Shop -> Mastercraft Sets -> Dessert Set. Note it is not Desert.
Info Links: http://forums2.battleon.com/f/fb.asp?m=22171031
Experimental Robocockatrice (Z-TOKEN)
Already mentioned in the wind section.
Location: Miss Fixit -> Who's Kamui?
Fu-Dog
Toggles between a one-hit attack that gives up 76.85% damage but has a high chance to Petrify the monster and a two-hit attack that has +4.25% BTH. The advantage that this has over Experimental Robocockatrice is that it will always attempt to Petrify when toggled and also uses the monster's CHA (supposedly), which a lot of monsters don't have, in its save roll instead of END (currently bugged to use the monster's END).
Location: Valencia -> Golden Giftboxes -> UltraRare Shop
Neko Waifer
Has a chance to Paralyze every turn.
Location: Celestial Haven -> Mind if I explore the town for a bit? -> Pet shop -> Advanced Shop
BulbaZard
Has a chance to do an attack with increased damage.
Location: Zard Hunter's Shop
Sabre-Toothed Grenwog
Toggles between pure damage and Elemental Vulnerability (EleVuln). Its EleVuln attack can inflict up to +31.43% if all hits landed.
Location: 6000 Z-Token Package
Carnation-in-Full-Bloom (SEASONAL)
Location: Snugglefest -> 2008
PikaZard
Location: Zard Hunter's Shop
Lepre-Chan (SEASONAL)
Location: Blarney War
Fairy Godmother
Location: Guardian Tower -> Guardian Shop
Scarab
Location: Warlic's Shop -> Mastercraft Sets -> Osiris Set -> Scarab Set
Model 294
Toggles between pure damage and Elemental Vulnerability (EleVuln). Its EleVuln attack can inflict up to +31.43% if all hits landed. The value goes up if you have the MechaKnight armor and shield equipped.
Location: Travel Map -> Sail East -> Mt. Thrall -> Hollow's Garage -> I'm here to kick some demon tail!
Aberrant the Exiled (RARE)
Location: None
Deatharrows Cat
Location: Valencia -> Golden Giftboxes -> UltraRare Shop
Vampoglin Lord (RARE)
Location: None
Nightmaregon
Location: Robina's Shop -> Quests -> Nightmare
Mini Nulgath (SEASONAL)
Already mentioned in the fire section.
Location: Location: Valencia -> Golden Giftboxes -> Rare Shop