Welcome, everyone! This will be an extremely quick guide on how to get a Rattata to level up quickly to 80 to travel to Hoenn. Let's begin!
This is going to be a really mini guide so as to get your Rattata ready for Hoenn, to be able to fight Youngster Joey. If you want to go to Hoenn, you need to capture any Rattata (it has to be yours) and you have to train it to 80 (or ask a friend to do it). However, I'll assume you have no friends you want to train it yourself without having to pay anyone else.
If you want to level up Rattata safely, I will leave you a few steps that will be very useful for you.
1.- Capture a Rattata with the ability Run Away. This isn't obligatory but it will ensure 100% success rate when you want to flee a wild pokemon battle. You can hunt one in Route 1 as in a single fight it will ALWAYS level up to level 38 or so.
2.- Visit the Bug Catching Contest in Johto and participate in it. Try to finish in the first 3 spots. You will obtain some PvE Coins.
3.- Visit the PvE Coin Exchanger in Saffron or Goldenrod City. Purchase an Air Balloon.
4.- Visit Fuchsia Gym. Purchase a TM Toxic.
5.- Travel to Mt Silver 1F, 2F or 3F. Equip Air Balloon to Rattata and teach it TM Toxic. Mt Silver 2F requires fighting some trainers but it's the easiest place to train it. Mt Silver 1F is also fine.
6.- Flee from all wild pokemon using Run Away and when you find a Quagsire which is level 52 or below, use Toxic on them. Then, keep attacking until they die.
If you have Air Balloon equipped, you will be immune to Earthquake, which is their only attacking move. Free and easy experience!
Before the method.
After only two fights.
We will repeat this process until our little Rat is at level 80 and we can fight Youngster Joey! All his Rattata are level 120.
Job is done! (keep in mind I used a different Rattata for this screenshot)
If you need a Video Guide on this method, please use this link.
We can easily destroy him by using a low level Geodude with Sturdy and Stealth Rocks (to ensure we can use it once), and then a Machamp with No Guard can oneshot his entire team with a single Dynamicpunch per Rattata.
Unleash your STAND Dynamic Punches to defeat Joey!
He will be waiting there, between the two Elite Four buildings. After you defeat Joey, you can now talk to the Hoenn Traveler and travel to Hoenn!
Big warning: Once you go inside, THERE'S NO GOING BACK UNTIL YOU BEAT HOENN'S ELITE FOUR. Good luck! Pack up your things , get ready, purchase anything you may need and go there!
I hope you enjoyed the guide and I hope you newbies are successful in your Hoenn Adventure!