Pet Training Kits

Would they work? I do assume yes.

Partners have their own training kits. The NA ones come with Partners and don't work... And aren't in the item shop yet.

What do they do anyway?

The partner training kits are probably similar to Pet Training Kits, where it randomly boosts/drops a rank of a few skills.

Hm, are they reliable?

What are you referring to by "they"? The pet training kits or the partner version of it. And reliable in what sense?

Both. And how often do they work for the better or for the worst?

50/50. There's better or worse. You'll get one of the two.

Read the page for more details, but basically at least 1 skill will increase, and there will never have more skills decreases than increases. Ex: if you used the pet version and your pet gained a rank in 2 skills, the max number of skills that'll lose a rank are 2, and it won't be the two that just gained a rank.

So its just a luck-based thing, huh...

Of course o-o Almost all cash shop items have some element of chance in it; nexon isn't making money by making sure players get what they want in 1 attempt :/

Just because there's a partner version doesn't mean the pet version doesn't work.