I believe my first evolution was probably Charmander to Charmeleon, back when I had my Pokémon Red, or was in blue..? Anyway, I had like 3 Pokémon at that time and 2 of them were ready to evolve, 2 or 3 levels left. I battled Gary, and Charmeleon was, by mistake, the first one on my party, so it evolved the first from the other one. So, yeah, that was really it.