It depends where you want to take your pet. If you ever decide that you want to hit the maximum STR and DEF boosts and have crazy HP, you first need to train to a sufficient level. For 1P Battledome success, the path is as follows:
-Train level using Terror Trove Scratchcards and Codestones/Dubloons when necessary until you can continue training your other stats.
-Train strength until you cannot continue to train it.
-Train defence until you cannot continue to train it. (These are due to level requirements of the schools, btw.)
-Train endurance until you cannot continue to train it.
-Repeat.
Avoid using the Lab Ray until you are level 51 or higher. If you get extremely bad luck, you can be zapped back to level 1, making it very frustrating to continue your training.
If you can afford it, you can substitute training Defence entirely with Armoured Neggs. Just leave your pet at Hunger: dying, feed it one A-Negg, then wait about two hours. It will go from Hunger: starving, back to Hunger: dying. This is the fastest way to train Defence, and will keep pace with even the most intense Strength training regime.
Try doing K-Quests as well. If the cost of a single K-Quest is below the cost of training 1 stat at your respective school, it's typically worth doing. He gives out UBs and 50k+ items occasionally. (This is a rumor, but it's been pretty consistent for me: The faster you complete his quest, the higher NP value item you will get if you do not get stats.)
I am under-experienced in 2P training. My only advice is to just look at max league builds and plan your training funds in advance so you can leap-frog between 2P wars.
Edited by splatzilla, 22 July 2011 - 03:49 AM.