Ok, I am gonna go through some things until I either get bored or until my partner is ready to watch netflix. Either one could come first here.
So starting at the top and working my way down.
Firstly, Lax seems to have gained at the expense of Chansey. This is a bit of a surprise to me, from people's comments I would have thought it would have gained at the expense of Tauros, but the stats dont seem to bear that out. So the big thing for Chansey that has changed from last year is a dramatic reduction in Reflect and Stoss on Chansey's move set.
In an ice Chansey dominated metagame, having an unparalysed Chansey against your opponents paralysed Chansey means sometimes it can feel like total dead weight. It is absolutely dominated by the enemy Chansey. On the other hand, Snorlax comes in easily against the paralysed Chan and can really mess up your opponents team in the process. So its easy to see why Snorlax would feel like a much more impactful pokemon if your opponent is playing freeze games and you arent willing to.
So in that situation you might think, ok so I will just drop Chansey. Which used to be a really strong option. However, due to the Body Slam change Chansey there's a bit of a trick these days. Because what you want to do is say, ok I will drop Chansey and instead I will paralyse my opponents Chansey and dominate them with my Snorlax. So what I want is a check to things that check Snorlax, that will lure in my opponents Chansey, allowing me to bring my Lax back. That way my Lax is taking weak hits from Chansey, and my opponent's Lax check is taking stronger hits from Snorlax, but their Lax check never actually hits my Lax. We are looking for something that consistently checks the likes of Snorlax and Cloyster and to a lesser extent Gengar and Eggy. And if you can think of a better option here than a Chansey then maybe you are better at RBY than I. So I guess I kinda predict an upswing in reflect Chansey usage (which tbh I think I have already started seeing) in the next few months. Which may boost Chansey's popularity a bit again.
This is why I put Chan at 2 over Snorlax. I think Lax doesnt work without Chan's support, but that Chan can get away with replacing Lax with things like Cloyster and Rhydon. At least more easily than you can replace Chan with like Porygon or something. And even if you dont want to do that, just chuck sing on it and get rid of your god damn Eggy. Chansey just does so much and does it all so well..
The Snorlax Eggy correlation I think is an interesting one. Personally I think this may be about the desire to control games (which I would argue you guys are taking too far if youre voting Lax ahead of Tauros). So back in the long times ago when everyone other than me sucked at RBY, Lax was my favourite mon to use, because it gave me so much security. Whatever the fuck you are dealing with, Lax will either beat it 1v1 or trade with Self-Destruct. This is very desirable if you are way better than whoever you are playing against. On the other hand, Eggy can be hilariously unreliable. Sometimes it will D-E to kill a paralysed Zam, sleep your opponents Eggy then Explode on their Chansey. Sometimes, it will FP a lot and not even get its sleep off before exploding on a Starmie and not even kill it. When you are way better than everyone else this is not really what you want out of a mon.
Now the funny part is that Snorlax is great partly because of Self Destruct, but Eggy is godawful because of Explosion. The key thing being that Eggy needs to Explode to be useful, whereas Snorlax doesnt. So firstly, Explosion always simplifies the game, which is generally better for the weaker player. It's very easy to explode on a pokemon and then realise that actually need your Eggy to deal with your opponents Exeggutor for instance. With Snorlax if you dont want to simplify the game, then dont explode. But if youre in trouble then do it. Eggy doesnt really have that luxury. And because of that with Eggy the calculation of predicting an Explosion is pretty much always straightforward, and even a very novice player will get this right against you often enough. With a Lax the downsides to getting that wrong are much worse. And you dont even know if your opponents Lax is even carrying it!
I think this also carries on to Pokemon like Victreebel and Slowbro. Both are incredibly unreliable mons. Victreebel in particular being very cookie cutter in its use, and it makes it hard to differentiate yourself from your opponent when you use it. Basically everyone knows exactly how to use Wrap these days, and the only reason to use it is for that golden par mie, rhydon matchup (or even better, the slowbro matchup). Personally I think there is a lot of potential in the way Victreebel can provide free switches, although there is a huge downside to that because the free switch to whatever you get in is paid for with the very high cost of ever switching Vic in.
Slowbro is a much better mon than most people give it credit for. It requires a lot of prediction to work it well. Dont just Amnesia 3 times then rest and expect to sweep with it. It should aim to come in at least twice. Paralyse it's counters on the first pass and do the damage on the second. You only need two Amnesias to be doing enough damage to Chansey that it isnt really much of a threat to you any more. Boltless Chansey is just a dream come true for Slowbro. You can use it early in the game to paralyse stuff or late in the game as a cleaner (or both). Reflect Bro is pretty cool too, but I think at the moment its pretty hard for that to work.
Ok, Netflix time.