The games I would recommend hunting in are Let’s Go Pikachu & Scarlet.
Honourable mention to Sword. While the shiny rate in Dynamax Adventures is 1/300 ( or 1/100 with the Shiny Charm ), it takes so long to complete that factoring in the time makes it inefficient and honestly boring to do repeatedly. You’re also never guaranteed to encounter the Pokemon you are looking for if you choose to Shiny Hunt through DA.
Let’s Go Pikachu —
The Let’s Go games have a unique feature known as the Catch Combo. A catch combo occurs when you catch the same Pokemon repeatedly. To maintain a combo, you need to stay in the game, try to only encounter the Pokemon you are chaining ( if you encounter a different Pokemon, run, don’t throw a Pokeball or let it flee or the combo will break ), and don’t let the Pokemon you are chaining flee.
At a combo of 31+, the shiny odds are 3/1024, or around .3%. With a Lure active, this increases to .31% ( 13/4096 ), with a Shiny Charm it is .34% ( 7/2048 ), and with both a Shiny Charm and Lure it is .37% ( 15/4096 ).
On top of the increased shiny odds, using the Catch Combo method also greatly increases the chance of encountering the Pokemon you are combo-ing ( 50% at 31 or higher ). While Eevee can only be found on Route 17 with a 5% encounter rate, this can be greatly increased, making it a relatively simple and engaging task.
Scarlet —
Scarlet & Violet are referred to as the easiest games to shiny hunt for a reason. This is due to two mechanics in the game — sandwiches and outbreaks.
Outbreaks are randomly placed around Paldea, and are areas where one Pokemon will spawn continuously in large groups as you defeat them. To maximize the shiny odds in an encounter, you should defeat / catch 60 or more of the Pokemon you are hunting. However, you must not defeat too many, or the outbreak will end ( I recommend staying at 60. You can reset the encounters if they’re not shiny by leaving the area or setting up a picnic ). You will get a message that there are not many Pokemon left from the original outbreak once you’ve hit the threshold of 60.
Outbreaks can be paired with a Sparkling Power Level 3 Sandwich to further increase odds. I’m not the most well-versed on how to build sandwiches in SV, but I do know that you must add at least 2 Herba Mystica to a sandwich to obtain Sparkling Power. To better understand how it works ( assuming you don’t already ), you can read through here for an in-depth explanation.
Getting into the actual odds. I couldn’t find info on how often Eevee specifically will spawn in an outbreak, but there are two biomes it spawns in — Olive and Town. Assuming you find an outbreak of Eevee in these regions and defeat or catch 60 of the spawns, the rates are : 3/4096 ( .07%, base ), 5/4096 ( .1%, with Shiny Charm ), 6/4096 ( .15%, with meal power ), and 1/512 ( .19%, with Shiny Charm and meal power ).
While these rates are theoretically lower than in Let’s Go, you must consider that for Pokemon in outbreaks, there will be a large amount of encounters at once, and resetting via the picnic method is quicker than running out of the area in LGP.
Edit : As pointed out in a comment below this post, there is another mechanic in SV that helps with shiny hunting. It is less of a way to increase shiny odds and more of a quality of life benefit, though. You can quickly clear through waves of outbreaks by sending out your Pokemon to auto-battle in Let’s Go! mode ( oddly not introduced in Let’s Go ). If you happen to encounter a shiny before you break 60 encounters, your Pokemon will actually not attack a shiny. This allows for outbreaks to be quicker, and for shinies to be easily noticeable within a large group of spawns.
Note : All of the information here can be found in the hyperlinked sources.
Secondary note : I didn’t cover the other games at all since they do not have as reliable or effective methods as the two ( technically three ) mentioned. That said, you could always use the Masuda Method ( feel free to read for an explanation and its rates in each game ) in any game to increase odds. However, it is generally a slower process than Catch Combos or outbreaks.
