Best nature for Treecko in Pokemon Emerald?

I think Rash is a pretty good nature.

Don't forget in Emerald types are defined as special/physical and not the moves themselves.

In Emerald Fire, Water, Electric, Grass, Psychic, Dark, Ice and Dragon are all Special while all other types are physical.

Most of Treecko's weaknesses are Physical type moves being Flying, Poison and Bug, while Treecko's Special Weaknesses are less being just Fire and Ice.

In emerald you run into a LOT of flying type moves so special defense down is fine. Yeah there is a fire gym AND an Ice user in the Elite 4 but they are easy weaknesses to cover.

If you don't want to risk the large weakness to ice later in the game maybe a Modest Nature would be better (Special attack up, Physical Attack down) since it is likely you will use a Flying type which is also weak to Ice, but if you plan on using something with Fire moves, Fighting, Rock or Steel just might as well stick with the rash nature.

It's only a 10% rise/drop which you can probably use vitamins to cover if push comes to shove :)

Best Nature For Treecko

For the best answers, search on this site https://shorturl.im/1eJZ0

Torchic- Hasty or Mild. Hasty will drop defense and raise speed. Mild will drop defense and raise Special Attack. My choice would be Hasty because speed is always benificial. Blaziken doesn't need defence because the things that hit him for super effectiveness are usually special (just avoid ground) Treecko- Mischevious. That will raise special attack and drop attack. Sceptile should be a pure special attacker Mudkip- Adamant. That will raise attack and drop special attack. Swampert doesn't need the Special attack, just give him waterfall instead of surf/hydro pump.

is calm a good nature for a Treecko