Chance of perfect IVs :
1/6 chance that the missing stat is in the right place. (1/6 = 32/192)
5/192 chance that the Pokemon will have perfect IVs anyway (missing stat = 31)
So 37/192 chance of perfect IVs.
Chance of HA = 3/5
Chance of perfect IVs + HA = (37/192) * (3/5) = 111/960 = 37/320...
I just finished completing my ribbon buddy Ampharos, so I can help you here!
Contests are not hard, the process is just long. There is no cap on how many Pokeblocks you can feed your Pokemon anymore (unlike in R/S/E) so you can literally just level them up until max without having to worry...
Different websites have different rules but RNG abused Pokemon are usually considered to be fine even on relatively strict sites. Cloning is a bit more controversial. As you can see from all the threads on this forum, both RNG and cloning are allowed on this site :)
I would say the most interesting things are the flawless Naive / Careful Method 4 spread, especially for Rayquaza. Another reason to RNG on R/S is to get a level 45 Kyogre / Groudon so that you can win the weather war (not sure how relevant that is now because of the pentagon rule). Apart from...