Pet Training
This is a bit of a work in practise, not so much an "informational" page as it is a guide page. I reckon we should make a category for "guides" where users can "ramble" in "their own words".
Contents
Initial Selection
Pet training begins by getting a pet worth training. If you're going to invest time in making your creatures more powerful, it stands to reason that you should first spend some time making sure the initial specimen is as powerful as possible.
There are a few aspects of your minions that you need to take heed of. First off, set yourself up a macro to activate the Animal Lore skill (as a tamer you should already have a fair bit of this, but if not, remember that humans get an inferred minimum of 20 points in every skill). Using this on your pets will grant you a detailed window which goes through their strengths and weaknesses.
A good way to find out how powerful a pet is likely to be before you tame it is to use Animal Lore and enter the information into the Pet Power calculator on UOCraft Pet Power
You can also work out your chance of controling a pet is using this link on UOCraft Pet Control
Skills
Any skill a creature has can be trained to either 90% of what it was before taming, or 100.0 points (which ever is higher). For example, a creature tamed with 144 Wrestling will have a training cap of 129.6 (144 - 14.4), while a creature tamed with 50 Tactics can only be trained to GM level.
Like Stats, these skill levels are subject to no overall cap - Some creatures, such as the Rune Beetle, can be trained to have over 800 skill points.
Wrestling, Tactics & Anatomy
A pet's ability to Wrestle improves it's chance to hit a target, while Tactics improves the amount of damage it can actually deal. To improve in these two skills your pet must fight something within about 25 points of it's own skill ranges.
Anatomy on the other hand can be trained by fighting against a target of any skill level. It tends to raise at a much slower rate, however. It improves your pet's chance of dealing critical hits.
Magery, Evaluating Intelligence & Meditation
Characters mostly rely on their Magery skill to determine their chance to cast a spell, however a magic capable pet is only limited by the amount of mana it has in reserve. A wild Nightmare, for example, will quite happily open up with Flamestrikes despite only spawning with a maximum of about 50 Magery.
Nevertheless, Magery does serve to improve the effects of some spells. For example, a pet with more skill is more likely to succeed when casting Cure or Arch Cure, and will be able to repair more damage with Heal or Greater Heal.
Evaluating Intelligence serves to boost the effects of most combat-orientated spells, improving damage dealt along with the duration of buffs or debuffs. The Meditation skill serves to improve mana regeneration, hence helping your pets to remain effective for prolonged periods of time.
It doesn't really matter what you fight for the purpose of improving these skills, as pets cast spells automatically in combat and do so whenever they find themselves with a shred of mana to spare. However a pet which has used up all it's mana will mostly cast lower level spells, hence reducing their chances of gaining Magery when they hit the higher skill levels. One solution to this is to fight creatures that spawn solo, hence allowing for some recuperation between kills.
Resisting Spells
A pet's ability to resist spells essentially makes it harder to inflict a debuff upon it. For example, at 100 skill, you will require over 110 points in Magery to inflict a Curse on your pet - and even if you manage it, it won't last anywhere near as long or lower it's abilities by anywhere near as much as if it lacked spell resist altogether.
This skill was traditionally very hard to raise until the destruction of the original Haven introduced Spectral Spellbinders. These are unique in that they only cast the types of spells which trigger spell resist checks (debuffs), and of those they only cast the spells that deal no damage. In terms of physical combat they are also extremely weak.
To train in this manner, simply wander the streets of Old Haven ordering your pets to "kill" the Spellbinders you see. As soon as you can, tell them to "follow" you again and the undead spirit will follow your pet blasting it with spells.
If you cannot find any Spellbinders, simply kill all the undead spawn in the area and a fresh wave will appear in short order. If you have a particularly weak pet you'll need to keep a close eye on it's health bar, a full Lower Reagent Cost suit helps maintain a lengthy session of Greater Heal spells (but be careful to conserve your mana as much as possible).
Once you've got as many Spellbinders as possible simply sit back and let them cast away. While their spells do no damage at all, the eight closest to your pet will be able to deal melee attacks, so you might like to take advantage and practise your Veterinary skill while you wait. Depending on the amount of monsters you attracted you should be done within an hour, perhaps a little longer should you wish to cap your pet's Stats while you're at it.
Poisoning
Guess Poisoning is a lot like Anatomy, target any type of enemy you wish and just keep belting them.
Healing
The only pet with the Healing skill is the Cu Sidhe. It will not only use the skill to aid itself but it's master as well, assuming you're in range.
It'll automatically use the skill whenever it's health level is below a certain amount (90%?), and continue until fully repaired. However, in order to train past 90.0 points, it must cure deadly poison.
An otherwise well trained Cu is quite capable of killing single Rotting Corpses indefinitely without intervention from it's master. Be warned that because the process of getting poisoned and then curing itself is very slow, it can potentially take months to reach Grand Master level. Many players choose not to bother, more still now that the Greater Dragon is a far more effective pet then the Cu Sidhe in terms of both giving as well as taking damage.
Stats
Use Animal Lore to check out your pet's stats. Your character's stats can each be trained to a maximum of 125, and this is also true for your pets. However, unlike characters, pets have no "overall" stat cap and so Strength, Dexterity and Intelligence can all potentially reach their maximums.
Pets gain stats by exercising their skills, but gain them far faster if using skills that are already capped out. A good way to get stats up quickly (particulary Dexterity, which can be very slow to train) is to raise Resisting Spells first, and continue to have spells inflicted on your pet after that has reached it's maximum.
Each time a creature gains in a stat, it will also gain in a related statistic - For example, improving Strength will also improve Hit Points. Therefore you want to tame a pet with the highest hit point total possible (so as to have the best starting point to train from), and the lowest strength value possible (so as to have the greatest number of potential gains to the hit point total).
An exception to this rule is when a creature's initial strength value can start at 125 or higher. As you won't be able to improve it any further, you therefore wish to tame a creature with both the highest strength and hit point totals possible. Similar rules apply to Dexterity (which improves Stamina) and Intelligence (which improves Mana).
Strength
Every time a creature gains a point of Strength it's maximum Hit Points will also increase by one. This also determines your pet's base damage output.
Dexterity
Every time a creature gains a point of Dexterity it's maximum Stamina level will also increase by one. The more stamina a pet has the faster it can strike and the faster it can travel.
Intelligence
Every time a creature gains a point of Intelligence it's maximum Mana level will also increase by one, which also improves it's regeneration speed.
Resistances
Use Animal Lore to check out your pet's resistances. Unlike your character (which starts with no resistances and gains them by donning armor), pets come with their own "base" resistances which vary between specimens.
Your character can improve his or her resists by training Resisting Spells (albeit by a very small amount) - While your pets can also train in this skill, they will not receive a resistance bonus from it. Hence they cannot improve their initial resistance levels at all - make sure the pet you choose to train starts out with the highest levels possible for that particular creature type (especially in terms of physical resistance).