Which Place In Pokemon Heartgold In The Johto Region Can I Level Up My Pokemon?
Personally, I would try Ice Cave (just before Blackthorn City) or perhaps even the dragon cave at the back of Clair’s gym. Alternatively, you could visit the Safari Zone, catch some rare-ish Pokemon and then trade them using the GTS. As the gym is Dragon type, I’d say get an Ice type or Dragon type Pokémon as these are super effective. Also, flaafy evolves at lvl 30 into ampharos. *EDIT* Try Ice Cave for training your Flaafy and Mantyke (Water is super effective against Swinub). There is also a guy near Mahogany called Vance (I think, just outside Ice Cave) who has a HootHoot and Pidgeotto and will fight you anytime, so that’s good for your Sudowoodo. And, near to where Sudowoodo was, there is a School Kid (Alan, I think) who has a Tangela and later a Yanma, and he will battle you at anytime too, so great news for your Pidgeotto. Add them to your Pokégear phone and call them when you want a battle. Certain gym leaders will rebattle you as well, but they are really difficult and I am un