Sleep and leads in RBY
If you are familiar with the RBY OU metagame, then you should be aware of the importance of sleep in the oldest generation. As a result, because the choice of the lead has a lot to do with the sleep game, having the lead advantage or disadvantage is now being given more credit. I'm not suggesting that leads are irrelevant, but ultimately, picking the correct one is something you pretty much have no control on over, because it mainly depends on the opponent's lead. In this guide, I will show you that, as much as having a lead advantage will often be relevant, having a plan around the sleep game, understanding the lead match-ups, and knowing what your team is capable of regarding this aspect of RBY is as important as leads are, if not more.
The very first thing to know about sleep in RBY is that a sleeping Pokemon doesn't attack the turn it wakes up. To make up for that, however, sleep lasts from 0 to 6 turns in RBY, while in the newer generations it always lasts at least 1 turn. The first mechanic implies that you will not be vulnerable to "surprise" wake ups after you put something to sleep. Let's say you would want to capitalize off a sleeping Exeggutor with your Tauros. If this situation had been applied to any of the future generations, had you known Exeggutor was waking up that turn, you would've probably switched Tauros out; in RBY, however, you will always be safe in this kind of scenario, because you'll be able to switch back to another Pokemon if the foe wakes up, thus preventing your active Pokemon from being hit.
This mechanic also makes slow Pokemon vulnerable to repeated sleeps. Imagine an Exeggutor vs Chansey match-up. If we were not in RBY, Chansey could survive Exeggutor's special attacks, wake up eventually, and use Softboiled that turn. Exeggutor could always pick Sleep Powder again though, but it would almost never be able to take Chansey down on its own. But in RBY, it's a different story. Because Chansey won't attack the turn it wakes up, Exeggutor will be able to put Chansey to sleep again, without letting it recover damage with Softboiled. In this case, Exeggutor has a much better chance to take Chansey out, as Chansey will be relying on Sleep Powder misses.
Something you will have to keep in mind and grasp is that sleep in RBY doesn't quite work like in future generations. In the newer metagames, sleep occurs because there is some sort of specific offensive or defensive purpose behind it, but hardly otherwise. Offensive purposes are akin to breaking walls, in the sense that the sleep inducing move is opening up the sleeper or another teammate by neutralizing the target temporally, because the sleeper is able to achieve that by baiting the intended target; or defensively, it is simply to prevent something from sweeping you. In short, sleep is based on the fact that your opponent should or could have no control of what's being put to sleep. However, in RBY, it's a different story. Basically sleep happens and nobody questions this. In RBY, sleep is always an instant 6 vs. 5, so if I had to tell you why sleep is basically mandatory in RBY, well it's just because 6 vs. 5, be it permanent or temporal, is better than 6 vs. 6; but in the first generation of Pokemon, sleep rarely follows a specific purpose.
Having said that, it's easy to realize now that the earlier you put something to sleep, the better. This way you can get the numerical advantage from the very beginning and start spreading paralysis "safely" (as paralyzed Pokemon may serve as sleep blockers as the battle goes on; more on this later). As a result, the lead selection revolves around the sleep game, but having a good lead match-up is often overrated. You should know what your team is capable of and choose a lead accordingly, but, more importantly, know what is going to be your play in the early sleep game, depending on the opponent's team, lead, and sleeper(s), because in RBY, you should usually be in control of which Pokemon on your team is taking the sleep. And that's the other key aspect why sleep is different in RBY: in RBY, there is no worrying about mispredicting the sleep attack and putting a RestTalk user to sleep or something else you didn't want to, strategically playing around Heal Bell, or similar things. The RBY sleepers always see the same small number of switches and you will likely put the same Pokemon to sleep regardless of if you pick the sleep inducing move the first or the seventh time you get your sleeper into play.
A bad match-up that forces you to do a first turn switch out shouldn't be hard to deal with in theory. It could mean that you score the sleep a few turns later than your opponent, or that you don't get that not-very effective hit or Thunder Wave on your opponent's sleeper; at worst, it might mean that you are put in the risk of having to let your only sleeper take the sleep before landing it yourself, or a generally more valuable Pokemon such as Chansey, Snorlax or Tauros. But that's, however, a case of team match-up rather that lead match-up alone. Dangerous Pokemon such as Snorlax and Tauros don't exist in the lead position because they would switch out against any of the sleepers or Starmie, and probably Alakazam too. Common leads generally pose no threat other than status and Explosion, but the latter is inviable early on barring double sleeper.
The leads you will be facing are Exeggutor, Jynx, Gengar, Alakazam, Starmie and possibly Hypno, which is very uncommon, but almost always as a lead otherwise. Now it's about understanding the match-ups and adjusting them to your team's capabilities. For example, if your lead is Exeggutor and your opponent sends a Gengar lead, there are two options. If Exeggutor is your only sleeper, you shouldn't probably take the risk, but save it for later to guarantee the sleep. On the other hand, if you have another sleeper on the team, you should probably fish for a Hypnosis miss to get a Sleep Powder or a Psychic off. In this sense, Gengar could turn out to be problematic against teams not packing Alakazam, because their only safe switch-ins against it are the sleeper (Exeggutor in this case) and other more valuable Pokemon that you'd rather want to keep awake such as Chansey or Snorlax, so you should count on these things when using the team. In short, know your team and the common match-ups, and have a solid and preconceived plan regarding the sleep game. Have a sleeper in your team (obviously), but also have a sleep absorber in mind. Know how you are going to act depending on your opponent's lead, sleeper, and plays, and take advantage of good lead match-ups as well, but don't go crazy choosing a lead either. Just try not to pick the same lead so that you don't get too predictable.
If you know the basics of RBY, you already know how dominant paralysis can be as well, but keep in mind that paralysis makes the target immune to other statuses, including sleep. This is something irrelevant for the most part in the newer generations, but not in RBY, where statuses are at their best and sleep is the most dominant. The known anti-leads, Alakazam and Starmie, pack Thunder Wave in their moveset, a really useful move overall, especially in RBY. However, paralyzing Chansey is not a good idea because it will be making her immune to freeze; spreading paralysis in general before landing your sleep move, has both advantages and disadvantages. I'm not saying it is a bad idea though, it's a matter of knowing the consequences and how to play around them, which has to do a lot with the teams and your sleeper(s). An example will help you understand what I mean: for instance, paralyzing the opponent's Alakazam makes sleeping with Double-Edge-less Exeggutor impossible if we only count this match-up, as Alakazam will easily be able to switch into Exeggutor and tank its hits with Recover. This should be taken into account because you might be banking your chances on putting something to sleep or at least capitalize off the situation (a predicted switch to a paralyzed Alakazam can be taken advantage of through your own double switch to an offensive Pokemon like Snorlax) on prediction then. On the other hand, you already know the advantages of paralyzing an opponent. A paralyzed Pokemon is a less useful Pokemon after all, and in the case of a paralyzed sleeper, a less accurate one as well, maybe letting the opposing Alakazam or Starmie lead to rack up more damage before being put to sleep.
To clarify, a paralyzed Pokemon won't always be a big obstacle for your sleeper(s); it depends on the match-ups. Jynx won't care much about a paralyzed Exeggutor for instance, as Exeggutor is 2HKOed by Blizzard and thus won't be switching into Jynx. Likewise, a paralyzed Starmie isn't usually a big issue for Gengar, which can now outspeed and 2HKO it with Thunderbolt; however, for Jynx, it will clearly be problematic, because Starmie is generally able to switch into Jynx all day.
When it comes to taking your opponent's sleeper yourself, the concept of the sleep absorber appears, that is, the Pokemon that you plan to let take the sleep. The choice of the sleep absorber is usually based on two criterion: the Pokemon's potential usefulness later on, and its probability of waking up in a few specific scenarios. Alakazam and Starmie are arguably less useful than other Pokemon such as Chansey, Snorlax or Tauros. The same thing can be said about Jynx and Gengar after putting something to sleep, and, to a lesser extent, Exeggutor. All of these besides Gengar, as they are Psychic-types, can tank Pokemon like Exeggutor without Double-Edge or Alakazam without Seismic Toss well, being able to wake up against them if healthy before dying. Alakazam and possibly Jynx also stand a decently high chance of waking up in time against Chansey and Starmie without a Water-type move. Gengar doesn't do as well in this regard, but instead, it keeps the ability to absorb predicted Explosions while sleeping. To a lesser extent, this can also be said about Rhydon and Golem. Gengar (and the Rock-types), however, should also be careful when switching into a sleeper, because Exeggutor and Jynx can both hit it hard with prediction.
Having said that, you shouldn't be switching sleeping Pokemon in carelessly during the battle, because that'd be the perfect opportunity for your opponent to get a dangerous Pokemon, such as Tauros, in for free. It also depends on the staying power and the health of the Pokemon (Rest is obviously another story, as both players know it always lasts two turns), but, for example, sending a sleeping Alakazam during the mid-battle will often lead to bad news. In general, unless you get a lucky early wake up, you'll be forced to let the active Pokemon die if you don't want or simply can't afford to switch another Pokemon into a Tauros attack. Keep in mind that a Pokemon that has been put to sleep is still doing something no other Pokemon can do, which is keeping the Sleep Clause on. On the other hand, you might be able to use this to your favor; if an sleeping Pokemon can lure offensive Pokemon, then maybe this makes a good way to get the Tauros mirror match-up, Snorlax mirror match-up, Tauros vs Snorlax, Snorlax vs Zapdos, or whatever match-up you could be looking for. This is more advanced stuff, however, and there is obviously a lot of risk involved.
But then, when and how is a Pokemon that has been put to sleep useful? Sleep Clause prevents another Pokemon from being put to sleep, so in some cases the sleeping Pokemon can be as useful as any other Pokemon. However, there are scenarios where you can prevent being put to sleep in another way; for example, your opponent's sleeper(s) could just be dead at some point of the battle, so the sleep clause doesn't matter anymore, or you might have paralyzed Pokemon able to take them on. It's important to distinguish between when you need it and when you pretty much don't, because if the latter, the sleeping Pokemon could be the best choice to switch into a predicted Explosion or to pivot, so that another Pokemon can get in safely against a dangerous Pokemon such as Tauros when you can't afford to switch into it directly.
To sum everything up, apart from the mechanics, there are two key differences between sleep in RBY and in future generations: in RBY, sleep is a lot more prevalent, but, on the other hand, it's also more predictable and easier to handle. As a result, knowing how to deal with sleep, and how to adjust your plays to the different match-ups and scenarios is key to succeeding in the RBY metagame.