For example, you can catch level 14 and 16 Magmars in the Burned Tower in HG/SS, but it evolves at level 30 from Magby.
If it's too hard to find all of them, all the ones in Gen 4, 8, or 9 could work
Here's a good list. It goes through all generations, and GO.
Hope I helped!
This answer goes as far up to Let’s Go Pikachu, Let’s Go Eevee, probably because the open world mechanics of Gen 8 and Gen 9 made it harder to know for sure.
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