Yep, Rotom is breedable. :)
Yes it's possible to RNG stationary Pokemon. In fact, that's the easiest thing to RNG and is what I recommend doing first if you're still learning to RNG-abuse. I say it's easy because it takes fewer steps than other RNG-abusing.
RNGing in the Safari Zone is possible, but to RNG wild encounter pokemon, you also have to take into account things called Encounter Slots, which is something only really controllable through the use of Sweet Scent. Here's a guide that includes Sweet Scent use and explanations of Encounter Slots:
http://www.smogon.com/forums/showthread.php?p=2830548
I would say, however, that the easiest way to get your flawless Cacturne is to breed for it. Encountering a wild Pokemon with flawless IVs is very hard - much harder than just breeding with a flawless Ditto and having the egg inherit IVs from it. RNG breeding is still complex, so if you can practice by RNGing stationary legendaries, I'd recommend doing that a few times.
Yes it's possible to RNG stationary Pokemon. In fact, that's the easiest thing to RNG and is what I recommend doing first if you're still learning to RNG-abuse. I say it's easy because it takes fewer steps than other RNG-abusing.
RNGing in the Safari Zone is possible, but to RNG wild encounter pokemon, you also have to take into account things called Encounter Slots, which is something only really controllable through the use of Sweet Scent. Here's a guide that includes Sweet Scent use and explanations of Encounter Slots:
http://www.smogon.com/forums/showthread.php?p=2830548
I would say, however, that the easiest way to get your flawless Cacturne is to breed for it. Encountering a wild Pokemon with flawless IVs is very hard - much harder than just breeding with a flawless Ditto and having the egg inherit IVs from it. RNG breeding is still complex, so if you can practice by RNGing stationary legendaries, I'd recommend doing that a few times.