Poison-type Pokemon are often considered some of the deadliest in the franchise based on the moves they can access.
Kanto was the start for the majority of Pokemon types. Poison-types were able to poison opponents and inflict damage over time, and nothing changed as the series moved to Johto and later Generations.
In Johto, only a handful of new Poison-type Pokemon were introduced. Most of them were originally found in the Kanto Dex. Thankfully, the list can expand as the Johto Dex did when HeartGold and SoulSilver released.
Note: This article is subjective and reflects the opinion of the writer.
Top 5 Poison Pokemon from Johto
#5 - Qwilfish
Qwilfish is not that great of a Pokemon, but it is one of four new Poison-types introduced in Johto. Qwilfish can be pretty quick and has a decent base Attack stat, but there isn't much special about it. It is a shame that it never received a powerful evolution.
#4 - Spinarak
Spinarak, a fun little spider with a smiley face on its back, is one of the new Bug/Poison-type Pokemon discovered in the Johto region. In the early portions of the Generation II games, Spinarak can be very useful. It can lower stats, poison opponents, and just cause some trouble until it evolves.
#3 - Ariados
Speaking of Spinarak evolving, here is Ariados. It evolves from Spinarak at level 22 and seems to have a similar stat spread, with its Attack being the highest at 90. It does what Spinarak does, except better. It has access to more status moves and moves to cause poison. Despite its lackluster stats, Ariados can be very annoying against a lot of trainers.
#2 - Nidoking
Nidoking was originally found in Kanto, yes, but this list needed a fifth Pokemon. In Gold and Silver, Nidoran can be found on Routes 35 and 36 in Johto. With, Nidorino it can also be found in the Johto Safari Zone in the remakes.
Of course, they can become the almighty Nidoking. That puts Nidoking in the Johto Dex, whether it is native to Johto or not. This Poison/Ground-type is a beast.
#1 - Crobat
First place goes to Crobat. Zubat, and Golbat, no matter how much of a nuisance they could be, they were solid Pokemon to have. At first, many believed they didn't need a third evolution. Especially the smaller ones in Crobat.
Now, Crobat has gained a ton of respect. It has 130 base Speed and the other stats are all solid. Crobat is one of the best Flying-types to make a run through Johto with.