Man, being a Pokémon trainer is hard…
Nah, you don’t even need more than one type of Pokémon, or more specifically you don’t need more than one Pokémon besides ones to use HMs in most of the games. If you only ever battle with one Pokémon it’ll generally become so over-leveled as long as you don’t miss out too many trainer battles that it’ll usually more than make up for any type differences. Plus because it’ll one hit KO most Pokémon before they can attack it’ll need healing less often.
Then again, you could argue there’s less fun in that =P
As someone who’s used that approach, I usually end up at some point where my main Pokémon gets KO’d by something it’s weak against, then I have to try desperately to take their Pokémon out with my super underleveled ones. It never hurts to have a backup or two.
Or a max revive.
only problem is that it will run out of pp for it’s moves, so a trip to the pokemon center isn’t really over looked. and don’t bother with moves that don’t do damage. It doesn’t matter what how much it lowers it’s defense, that’s a free invitation for a smack in the face. on the other hand If it puts it to sleep, poisons it, or confuses it, go for it.
I still use only one type. Steel.
*meteor mashes everything*
Most starters will learn bite or crunch. dark move that slaughters everything.