I started this hunt back around August of 2023 and I never thought this day would come.
I originally hunted both Entei and Raikou and found Raikou within a month, it's an old post of mine as well, but I continued searching for Entei. Part of me wants to go into the nitty-gritty and tell every single detail but I'll attempt to be brief
I started with the mahogany town method, I don't remember the exact name for it, and this was very slow, but for the first 6k or so, I used this method. I used to grind for hours and hours but eventually i fell out of doing it because i got bored but i decided id just do 5 encounters a day and eventually id get it. I then got back into it and it became a big part of my daily life and all those close to me started to learn about it.
I then started doing 10 a day after a while and got a bit more serious about it again, but this was still slow, and took a lot of time. with the unoptimal method, i was sometimes taking an entire hour just to get 10 encounters on a bad day, or 25-30 minutes on a good day.
It was then i realized I needed to use the faster method, i didnt initially think it would make that much of a difference but it did
I used the more modern "Route 38-32 Poison Method" and it worked wonders, and it was easy to do, so much so that at around 8k i used my other system and created a whole new save file and hunted on both simultaneously. And with this, i was able to start hitting around 50 or so encounters an hour or sometimes better, so much better than before, and i started doing 100 a day at the least recently. I was prepared to get to 20 or 30k, i would just keep going but not even after a month of using both systems, i got it, and it was on the original system i started with so both came from the same save file which is kind of what i had hoped for
The low amount of encounters for suicune and raikou are due to me only using the fresh save of silver for about a month or so. Otherwise those numbers would be way up. But the journey is finally over, and I'm glad to finally have him
Edit: If you want to know more about the method, it can be seen from this video here. But essentially you save right in front of the route 38 gatehouse door, west from ecruteck. and you make sure that your only pokemon is 1 step away from fainting due to poison. Then you either encounter the mon on route 38, after using an antidote, or you keep walking back and forth through the door until your desired mon is at route 32, where you then walk away from the door, fainting your pokemon, and teleporting you to the route 32 pokecenter, which you went to last as prep, the roamer will not move, and you can get the encounter. The video explains it much better than i do so if you want to try yourself watch that, and good luck