For many players, the fun of a new Pokémon game is in meeting new monsters and convincing them to join your team. Yeah, you might use them to dogfight other people in the streets, but they're still your friends! You've set out on your journey across the country to catch every kind of Pokémon you can find, and that's just what you plan to do!
Of course, sometimes this is easier said than done. Some Pokémon are much harder to catch than others, to say nothing of how frequently you encounter them or how difficult it might be to battle them. Sure, there are a different kinds of Pokéballs to make your job a little easier. But here's a few Gen II Pokémon you're going to have some trouble getting your hands on.
10 Heracross
Heracross is Johto's answer to the dangerous, single-stage Bug-type Pokémon Scyther and Pinsir. While it was never as popular as Scyther with fans, it's still a solid monster and even received a Mega Evolution in later games. You can find it in quite a few places in the game world by using the move Headbutt on trees, which knocks them out from where they were chilling in the branches. However, they have a fairly low catch rate to begin with, and headbutting every tree you see on the off chance of finding one gets tedious fast.
9 Aipom
This Normal-type got an evolution in Gen IV, allowing it to evolve into Ambipom if it knows Double Hit, but more recently it got its fifteen minutes of fame in the new Detective Pikachu movie. Those Aipom make it very clear just how scary Pokémon could be in the real world. Otherwise, it seems to be a fairly happy-go-lucky monkey that just so happens to have an extra hand on its tail. Aipom are another kind of Pokémon you can ever so rudely knock out of the tree it's living in, and they have a catch rate of a whopping 11.9%.
8 Murkrow
Murkrow is one of the first Dark-type Pokémon ever released and is among the many second generation Pokémon to receive an evolution in Generation IV. It vaguely resembles a witch, with a wide-brimmed hat and its bushy tail resembling the tuft of a broomstick. Murkrow is thought to parallel the Pokémon Misdreavus, as they both evolve when exposed to a Dusk Stone, and Murkrow is the only non-Ghost Pokémon to do so. It apparently brings misfortune to anyone who set eyes on one at night, but night is the only time you'll be able to catch one. Be careful, you'll need your good luck to get past it's 8.8% catch rate.
7 Wobbuffet
Wobbuffet are very weird Pokémon with an extremely specific and difficult to counter moveset. They're based on punching bags and training dummies, and they cannot hurt the opposing Pokémon unless it's attacked first.
It's ability, Shadow Tag, prevents its opponent from fleeing or switching. Then its entire moveset consists of Safeguard (which protects against conditions), Mirror Coat and Counter (which reflects moves back with double the damage), and Destiny Bond, which will take your Pokémon with it if Wobbuffet faints. It also has a fairly low catch rate of 11.9%. Getting one of these will be an ordeal.
6 Misdreavus
Misdreavus has the dubious honor of being the only Ghost-type Pokémon introduced in the second generation games, and it's seen as kind of a parallel to Murkrow. It's a saucy little spirit that specifically likes to bite people and pull their hair because it feeds off of their fear. They can only be found inside Mt. Silver at night, and Mt. Silver can only be accessed after completing the Johto route and the Kanto post-game. That's a lot of content to lock your only Ghost behind, and it makes Misdreavus particularly hard to catch.
5 Skarmory
Skarmory is a beefy, defensive Flying-type Pokémon that, frankly, shouldn't be able to fly. Not only does it probably weigh a heck of a lot with all that metal plating, but look at its wings. No wind resistance whatsoever. Not that Pokémon ever make sense but really.
Apparently its wings grow hard from being scratched constantly by the brambles where Skarmory make their nests. You think they could just not nest somewhere sharp. Skarmory are exclusive to Pokémon Silver and can only be found on Route 45, with a catch rate of 7.7%, if you want this airliner of a Pokémon.
4 Mantine
Mantine is one of the very few Pokémon that require another Pokémon in the party to evolve from it's prevolution, Mantyke. As seen in some of Mantine's sprites, it has a special bond with the Pokémon Remoraid, and will only evolve if one is nearby. Of course, in Gen II Mantyke wasn't around yet and you could catch these guys in the wild, with a little luck. They're exclusive to Pokémon Gold and can only be found on Route 41. They do have a bit of an unfavorable type combination, being Water/Flying, but just look as its little face. You know you want one.
3 Larvitar
Larvitar is the first stage of Johto's pseudo-legendary line. It has a cocoon stage despite not being a Bug-type Pokémon, with it's evolution Pupitar looking more like it wrapped itself in sheets of metal. They eat rocks and dirt, and are only found inside Mt. Silver presumably excavating deep caverns as they gorge themselves on enough minerals to grow strong.
Strangely, it's catch rate is slightly higher than some of the Pokémon above, but getting to Mt. Silver is a trial all on its own and it isn't easy to track one of these guys down.
2 Lugia/Ho-Oh
The box legendaries of Gold and Silver are much like the other major legendaries in the games. You have one climatic encounter with them and they tend to be very powerful, sometimes forcing you to knock them out or white out yourself. They have a low catch rate, of course, but if you're not above save-scumming it's entirely possible to catch one with a little patience.
1 Legendary Beasts
The trio of legendary beasts includes Suicune, Raikou, and Entei. According to legend, three Pokémon died when a bolt of lightning struck the Brass Tower in Ecruteak City, which was only extinguished in the following rainstorm. The three Pokémon were revived by Ho-Oh and are supposed to embody the three elements of the disaster: Water, Electricity, and Fire. The legendary beasts roam the world, sometimes appearing in places on the map where they can be encountered. However, they can be very difficult just to track down and they have a tendency to flee from battle. In addition to their 3% catch rate, they're some of the hardest Pokémon to catch.