You can't compare Raids with Challenge Modes and you cant mesure skill from some boss kills, most of them take time, skill is not the main factor.
The most important thing for challenge modes is to find people who want to do them and investthe time to try over and over until you get the perfect try. Setup matters a great deal too, tho its possible to get gold with nearly all compositions.
I've done them all more than once with a holy pally. For starters, gear does matter even though it's downgraded to 463. A 476/489/496/502/509 etc. piece with 2-3 sockets is way way better than a 463 piece with 0 sockets. Same goes for items with ideal itemization for your class (Itemization for cmodes is a lot easier to attain than it is for raiding).
After that, find a group with good buff coverage and decent players that are willing to learn the fights, watch a few youtube videos to learn the basic strats of each, and each one will take maybe 1-2 hours for the gold.
I'd recommend shadow pan monastery first, and stormstout brewery last