>>58837167Its historically rare, but it was a particular issue in Sinnoh, and to a lesser extent Hoenn.
Ignoring starters, Kanto had a version split between Arcanine and Ninetales, Rapidash, Flareon, Magmar (as a version exclusive), and Moltres to choose from. So that's 4-5 lines in the main playthrough, depending on the version and not counting trading.
Hoenn had Torkoal, Camerupt, and Slugma to choose from. Not the absolute worst, but Hoenn's regional dex is also 50 pokemon larger than Kanto, so it shouldn't have regressed like it did, and the regional dex theoretically could've been as large as the developers wanted. Like I was saying, it should've utilized the reuse of Pokemon lines more to round that out better.
Worst was Sinnoh's regional dex in DP, which literally only had Rapidash. There's no excuse for that.