Depends totally on the intended move set. Move set is always key before deciding on the nature. Modest/Timid are the best two options for an all out special attacker for any Pokemon.
Adamant/Jolly are the best two natures for an all out physical attacker for any Pokemon. Mixed move sets begin to get a bit messy, as normally you would pick a different nature to the ones already mentioned as you. If you're wondering what nature is the best for your Charizard, we've got you covered on that front.
What are the best natures for Charmander, Charmeleon, and Charizard? Dragon Dance is Charmander's best move for setting up a sweep, which makes it an obvious choice to base a moveset around. Flare Blitz is Charmander's main attacking move, being its most powerful STAB move by far. Thunder Punch complements Flare Blitz quite well, doing a good amount of damage to most Water-types.
In the last slot, two options can be considered. Brick Break is the main option. Charmander, Charmeleon, and Charizard's best stats are Special Attack and Speed, making it perfect for a special sweeper, especially with one of the natures above.
Pokemon Brilliant Diamond and Shining Pearl Charmander is a Fire Type Lizard Pokémon, with a 5.9% Chance To Catch with a regular Pokeball. Charmander can be found with Blaze as an Ability and has a Medium Slow growth rate with a 1 Speed EV Yield. We recommend the Hasty Nature, based on 309 combined Base Stats.
Best nature for Charmander? I'm on Day 5 of hunting for it's shiny but took a break and noticed you can set the nature for 10k. I'm wondering what best nature is. I'm hoping Timid so that I can also hunt Gastly.
For Pokemon FireRed Version on the Game Boy Advance, a GameFAQs message board topic titled "Best Nature for Charmander?". I would say any nature that boost Special Attack, such as Modest, Mild, etc. I say this because Charmander's HA is Solar Power which boosts Special Attack in Harsh Sunlight.
So if you have a Special Attack boosting nature along with Solar Power, you'll have a very strong Special Sweeper beast (since Speed is another high stat of the Charmander evolution line, so I would not suggest a Quiet. What is the best nature in Pokemon Sleep Charmander? Based on their effects, the best Natures in Pokemon Sleep are Gentle, Sassy, Careful, and Calm. These Natures have a higher chance of triggering Pokemon's main skill, which can be a lucrative outcome for recovery, EXP gain, and resource gathering.
For Pokemon LeafGreen Version on the Game Boy Advance, a GameFAQs Q&A question titled "What do you recommend are the best nature for charmander bulbasuar and squirtle?".