Grass-types who can make use of the Dig and Earthquake TMs are a good start, though you are unlikely to have access to the second. In fact, teach Dig to as many Pokémon as you can. A Dragon-type that know Flamethrower would also be a great asset, especially against Magneton.

[He's hoping that not using one that's part Flying-type is obvious.]

Also, while I cannot compare this world to any sort of videogame, I must mention that Elite teams were not an option for more than a year after we started arriving. Neither was visiting Kanto, for that matter.

Underestimating any Gym leader's Elite team would be foolish, yes. They know their type well enough to compensate for any weakness, after all.

[Which he'd expect from a leader, really.]

The train was not running, and neither was the boat. In fact, at first the locals spoke very little of other regions. There were fewer species living in the wilderness, too. This land has changed quite a lot, in five years and a half.