>>15902240 >What is chaining?
When using the Pokeradar under extremely certain circumstances, one can increase their probability of encountering a shiny in grass patches. This is the more tricky method of the three, as it requires that you follow certain rules in order not to break your "chain" or "streak". The higher your chain, the more likely it is that you'll encounter a shiny. While a faster method than randomly searching in the friend safari, pokemon in the wild are not guaranteed any sort of IVs and will not have their hidden abilities. It should be noted that you cannot use the Pokeradar in the friend safari, but this is made up for by the (supposedly) higher shiny rates in the safari. See the guide in OP for more details.
>Which method should I use, then?
It mostly depends on your preference and what you want out of a shiny. MMing is the obvious choice if you're planning on building a competitive team with you shiny, since it allows you to have influence over nature, ability, and IVs. Safari hunting is the next best choice if you don't want to spend weeks MMing but still want a specific pokemon with some guaranteed stats and the chance at a hidden ability. Fish chaining is a good choice if you just want a shiny to boast about or use as trade fodder as they're the easiest to catch. Pokeradar chaining comes in at the bottom with it being hard to do and not guaranteeing much else besides a higher probability and getting a specific pokemon. It would seem this is only useful if you can't find the pokemon you want in a safari, don't want to spend loads of time MMing, don't particularly care about IVs/Nature/Ability, and are good at keeping a chain alive.