Charmeleon in depth
A lizard called Lizard
The Japanese name is リザード, “Lizardo”, which is the English word lizard transcribed into katakana and little more. No pun, no double meaning, none of the charm found in other Kanto lines: the creature is a lizard and its name is Lizard. The Western name, on the other hand, was invented for the localisation by combining char, as in burn or turn to charcoal, with chameleon. The problem is that it has nothing to do with a chameleon—no independently moving eyes, no skin colour changes, no projectile tongue—and the choice is explained solely by the rhyme with Charmander and Charizard.
The design is credited to Atsuko Nishida. The visible reference is the lizard and, by association, the fire salamander from European tradition, the amphibian said to be born from flames. The crest at the back of its head is the detail people comment on most, because it resembles that of a Parasaurolophus, and it is the first time anything like it appears in the line: Charmander doesn't have one, while Charizard replaces it with two straight horns.
The same Pokémon as Quilava
There's a coincidence that tends to go unnoticed. Quilava, the middle stage of Johto's Fire-type starter, has exactly the same six base stats: 58 HP, 64 Attack, 58 Defense, 80 Special Attack, 65 Special Defense and 80 Speed. Not similar—identical. Both are pure Fire-type, both total 405 and both evolve into a Pokémon with 534. When Game Freak designed the second generation, it copied the template and changed the animal.
The difference is in the move list, and there's no tie there. Here you get Dragon Breath at level 12, Fire Fang at 19 and Slash at 24, as well as a TM catalogue that includes Dragon Claw, Dragon Pulse and Outrage. That access to the Dragon type comes from its Egg Group and the line's thematic connection, not from its typing, and it is what gives it an answer against opponents that resist Fire.
What changed under the hood
In the first generation, Special Attack and Special Defense didn't exist as separate stats: there was a single Special value, and Charmeleon's was 80. When the second generation split the two stats, the 80 stayed on the attacking side and Defense dropped to 65. That made the species considerably frailer than it was in Red and Blue, where that single 80 helped it both deal and take damage.
Abilities arrived later, in the third generation, and hidden Abilities later still. Blaze was added as the common Ability for all starters, while Solar Power appeared as a hidden alternative, trading HP for power and only working while sun is on the field. It's the only one of the three changes that gave it anything genuinely useful.
When it makes sense not to evolve
Twenty levels of usefulness don't amount to much, and the level-up move list confirms it: after Flamethrower at 30, the next moves are Scary Face at 37, Inferno at 48 and Flare Blitz at 54, all of them already with Charizard on the team. Deliberately staying here only holds up in formats that reward not evolving, with Eviolite making up for that 58 Defense. In a normal playthrough, the sensible response to the evolution screen is to let it go.