Sigbog is an avid gamer whose passion for Pokémon was reignited by "Pokémon Go" and now "Pokémon: Let's Go" in turn.
Chansey Power Leveling
Opening the Cerulean Cave
After you beat the Elite Four (plus the Champion), you open up the Cerulean Cave. This is the cave notorious for being the location where you find and catch Mewtwo. However, this cave is jam packed full of other goodies and reasons to explore.
The Pokémon that spawn in the cave are high level, and rare Pokémon can spawn there. The most important of which would be Chansey. Catching a Chansey nets you an awesome chunk of experience and that will be the cornerstone of power leveling.
Finding the Cerulean Cave
The Cerulean Cave can be found just outside of Cerulean City. You likely saw it earlier in the game but had no means to get there as it's blocked off to you by a little ledge. First, get on over to Cerulean City. Before leaving, be sure to stock up on Ultra Balls. To get to the cave, simply go north of Cerulean City over the bridge. You'll have a bit of water on the left where you can use the Sea Skim Secret Technique to enter the water. Go back down south a little bit and you'll see the cave off to the left where you'll be able to get off and enter.
Getting to the Right Spot in the Cave
I've found the first area of the Cerulean Cave is both too small and seems to spawn Snorlax instead of Chansey. I prefer to go to another area with more room, more items, and of course, regular Chansey spawns.
As soon as you enter the cave, you have to use the Sea Skim technique. Get off at the first point you're able to, which is a very short distance away. You'll see a ladder right there. Go up and you'll be in a large room with a lot of ladders.
This room is my preferred location to hunt for Chanseys being just a short distance from the entrance. Chanseys spawn quite frequently in the area. But it's also a large room that's easy to wander around and it's easy to dodge other Pokémon spawns. It's also full of item spawns you can check.
This area is covered with little glowing spots where hidden items can spawn. While running around waiting for Chanseys, try to run from spot to spot checking for items. Your partner's tail will shake if there is a hidden item there. They should respawn every day. You can get some great items from these locations including Golden Berries or even a Master Ball!
Item Spawns in the Glowing Spots
Starting Your Catch Combo
Now that you're in position, it's time to start racking up your catch combo.
Catch combos are a combo of catching the same Pokémon over and over again. They increase the amount of experience and items you get, as well as increasing the likelihood of rare and shiny spawns. Catching a different Pokémon, having a Pokémon run away from you, or turning off your game will break your catch combo so be careful! Fleeing from an encounter yourself, or sleeping your game will not break a catch combo though. For more details on catch combos, check out my guide on catch combos and shiny Pokémon.
To start, turn on a Max Lure to increase the chances of rare Pokémon spawning, like a Chansey. I'd also begin racking up a catch combo on a non-Chansey Pokémon to increase your chances further.
As soon as a Chansey spawns, catch it and begin your combo! From that point on, just wait until more Chanseys spawn and continuously catch them, racking up the highest combo you can.
I recommend running away from any encounter where Chansey has broken out of 2+ Pokéballs so you avoid having them run away on you, breaking your chain. Chansey can be tough to catch, so this will be quite annoying, but worth it to keep your chain. Your catch chance will increase though as you catch more. At 50 and 100 Chanseys caught, you will get a significant increase in your catch chance.
Prioritize Chanseys with red or blue effects around them, that means they are larger or smaller, which grant extra experience/items when caught.
Catch Combo Experience With a Chansey
Using Co-Op Mode
To maximize your experience, and catch chance, you can switch to Co-Op mode.
Simpy take off your Joy Cons and shake the second one when you're on the catch screen. It will open up a "Support Trainer" by splitting the screen in half and giving each player the chance to catch. This means you can use two berries, two Poké Balls, and throw with each player. If you throw simultaneously, you'll get a special catch sequence that both increases the chance of catching the Pokémon as well as increasing the experience you get by granting a "Synchronized Bonus."
Given that Chansey can be pretty hard to catch and having one run away will break your catch combo, this is incredibly useful and I highly recommend it.
Paul on July 01, 2019:
For the part that talks about running away after it breaks from two balls, there actually is a way to know when a pokemon is about to run. A pokemon has two animation, sometimes more. You can view all animations in the pokedex. A pokemon is about to run when it does it's second animation and it's cry. The rings will also still show when it does this animation. Run before it does