One-hit KOs

Paralysis

Sleep

Paralysis has two major effects on the victim: (a) a drastic reduction in Speed, and (b) the possibilty of full paralysis, making it impossible to attack.

Speed Reduction

The short answer is that, when no other Speed modifications are in effect, the PAR status change reduces the victim's Speed to one-quarter of its normal value (1).

However, things get considerably more complex if Speed modifying attacks (eg, Agility) are used on a paralyzed Pokémon. For a full explanation, please read the Speed and Burns sections on the Statistic Modifiers page.

Full Paralysis

Each round that a Pokémon is afflicted with the PAR status change, there is about a 25% chance that it will be fully paralyzed and unable to attack (2).

Switching does not remove either the PAR status or the Speed penalty.

Rest removes the PAR status and any chance of full paralysis (even after the Resting Pokémon wakes up). However, it does not remove the Speed penalty. Once the PAR status has been removed, though, the penalty becomes like any other statistic change, and can be removed by switching or by Haze.

Haze, when used by a paralyzed Pokémon's opponent, clears away both the status change and the Speed penalty. When used by the paralyzed Pokémon, Haze will remove the Speed penalty (but not, of course, the status change). However, if the paralyzed Pokémon then switches away and returns, the penalty will again be in effect.

Rest removes the PAR status and the Speed penalty.

Slowing the enemy down and preventing his attack 25% of the time may not seem like a big deal, but paralysis is a serious contender for the 2nd most debilitating status change, especially in Pokémon Stadium. FRZ is clearly the most desirable: a frozen Pokémon is as good as fainted. PSN and BRN are usually not even worth consideration. This leaves SLP and PAR. In the Red, Blue, and Yellow games, sleep can incapacitate for up to 7 attack turns, a devastating advantage. In Stadium, however, maximum sleep duration is only 3 attack turns: even if you successfully put your opponent to SLP (a gamble for everyone except the Paras series), there is a 1 in 3 chance for an instant wake-up, making your effort a waste of time.

Paralysis, on the other hand, is permanent, barring the intervention of Haze or Rest. The 25% chance for full paralysis is not terribly high, but it definitely tips the odds in your favour.

The importance of the Speed penalty should not be overlooked. The first time that both your Pokémon and its opponent are one hit away from fainting serves as a powerful lesson about the importance of Speed in combat.

Also, a number of attacks are most effective when the victim is slower than the attacker. One-hit KOs, for example, will have no effect unless the victim's Speed is equal to or less than the attacker's. Attacks that have a chance of making the victim flinch will only do so if the attacker is faster than the victim. Multi-turn attacks like Wrap and Fire Spin are particularly effective (and frustrating!) when used repeatedly by a Pokémon that wins the initiative each time. Paralyzing the enemy makes these techniques possible for slower Pokémon, but it serves a defensive function as well: the enemy will have less success using these attacks on you.

Paralyzing attacks are not just for slow Pokémon, however: Electrode can be invaluable to his teammates by Thunder Waving as many of the enemy as possible before fainting.

No Pokémon that learns one of these moves can learn any of the others. Glare affects Ghosts (despite being a Normal attack), so it and Stun Spore are functionally identical. Whether to include either of these in your Pokémon's moveset is a matter for your own judgement and experience to decide. In general, it's not like the Ekans series is overflowing with good set-up attacks, and besides it's pretty cool (in a Rudyard Kipling sort of way) for a big snake to hypnotize its opponent before striking.

However, every Pokémon that learns Stun Spore also learns the equally-accurate Sleep Powder. One factor that may help you decide here is whether you plan to do most of your battling in Red, Blue, and Yellow (go with Sleep Powder), or in Pokémon Stadium (Stun Spore may prove more useful).

Thunder Wave is the choice for paralyzing. It's nearly 100% accurate, and can be learned by every Electric type, as well as several Normals, Psychics, and even a few Water Pokémon. The only drawback is that it has no effect on Ground Pokémon.

Body Slam and Lick have a 30% chance to paralyze, while all Electric attacks (save Thunder Wave) have a 10% chance to paralyze. None of these moves serve as a reliable means of producing paralyzation, though any chance for a useful side effect adds to the value of an attack.

Does the strangeness with Agility apply to Stadium as well?

Is there anything about Pokémon that determines their likelihood of fully paralyzed rounds?

The following tests were made of the hypothesis that paralysis multiplies current Speed by one-quarter.

Pokémon1 Speed: 324 (x1/4 = 81)
Pokémon2 Speed: 82
After PAR, 2 was faster than 1

After a quick Shark adjustment...

Pokémon1 Speed: 324 (x1/4 = 81)
Pokémon2 Speed: 80
After PAR, 1 was faster than 2

Pokémon1 Speed: 80 (x1/4 = 20)
Pokémon2 Speed: 19
After PAR, 1 was faster than 2

After a quick Shark adjustment...

Pokémon1 Speed: 80 (x1/4 = 20)
Pokémon2 Speed: 21
After PAR, 2 was faster than 1

Pokémon1 Speed: 16 (x1/4 = 4)
Pokémon2 Speed: 3
After PAR, 1 was faster than 2

After a quick Shark adjustment...

Pokémon1 Speed: 16 (x1/4 = 4)
Pokémon2 Speed: 5
After PAR, 2 was faster than 1

Nine samples of approximately 200 rounds each were observed for eight different paralyzed Pokémon. Full paralysis occurred on 26.84% of the total 1919 rounds. The lowest sample proportion was 21.2%; the highest was 33.0%.

To test the possibility that something about Pokémon determines their proportion of fully paralyzed rounds, we examined a broad range of characteristics that varied among the subject Pokémon, including: Level, real statistics, base statistics, stat exp, Diversification Value (ie, "genes"), and species. None was found to vary systematically with the observed frequency of full paralysis.

We believe that the most likely explanation for the 11.8% range among sample proportions is sampling error (ie, "pure chance"). Supporting this view is the fact that one of the eight Pokémon was tested twice. In the first sample of 203 rounds, full paralysis occurred on 21.2% of them. In the second sample, the Pokémon was fully paralyzed on 28.25% of 223 rounds.