Need help picking a species for a monk build

Are you using the Star Wars mechanics but standard D&D flavor or is it set in Star Wars?

Well in terms of that description picking a small sized species is probably going to fit the character idea.

If you want to be nerdy I think Jawa would be a good pick. Now at level 2 monks get a mystic vow called Vow of the Focused "You can substitute Strength, Constitution, or Intelligence (chosen when you take this vow) for Wisdom or Charisma for your monk class features, except for other vows and Monastic Tradition features." So you can use your intelligence when determining your ac.

If your set on being a medium sized species perhaps a Kel Dor would be a good fit. You can think of it as being the asthmatic kid in a sense. Then in character you can say now that your character has a breathing device to keep the asthma under control your character can focus on improving themselves.

What about a Class iv Droid as a species?

They get +2 Con, +1 Dex or Str, get Martial Protocol.

You have proficiency with light and medium armor as well as two simple or martial blasters or vibroweapons of your choice.

This couples up well with the Monastic Order, Crimson Order, which provides the Crimson Armaments

Crimson Order: 3rd level You gain proficiency in light and medium armor. If you are already proficient in light and medium armor, you instead gain proficiency in heavy armor. Additionally, you can now gain the benefits of your Martial Arts and Unarmored Movement features while wearing armor as long as you are not wielding a shield. Additionally, you’ve learned to adapt to new weaponry. Over the course of an hour, which can be performed during a short rest, you can perform a kata with a weapon of your choice. You gain proficiency in that weapon if you do not already have proficiency, and it becomes a monk weapon for you. You can only adapt to one weapon at a time, and if you attempt to adapt to another weapon you immediately lose your proficiency with the chosen weapon.

So you have an armoured warrior who can use heavy armour, but still be fast, using an Auto Cannon as a Monk weapon, getting the Rapid & Burst actions on a Bonus Attack.

Using your Monk Vows on fighting styles, you can improve on your Gun-Fu even further or take other options. I like to take tge Onslaught Style, as it means you can Dash as a reaction. With Monk speed, you can cover unseemly amounts of distance fast.

Check out the Kage race! I have a player using that as a monk class and it’s a nice fit

It could be fun to play that character as a species that is traditionally viewed as strong (like a Wookiee or Trandoshan) or as one viewed as weak (like an Anzellan or Gungan, even though later are actually quite strong lore-wise). Aside from that, it might be wise to look for a species that increases Wisdom or Dexterity, but I don’t think that’s absolutely necessary.

A kaminoan monk might be interesting. The long and lanky willow of a nerd. A nemoidian are often viewed as opportunities and craven, so spending money for private martial art lessons might be interesting. Stack on a couple levels of rogue and you can sneak attack when you go to shake someones hand or bow respectfully into a headbutt.

If you want inspiration for styles, look up different formal matial arts styles in sw. https://web.archive.org/web/20091016032015/http://wizards.com/default.asp?x=starwars/livingforce/swlf20040415a (Old link from the RCR (3.5) days

For my monk I went Kiffar. You get the species traits for +2 to dex or strength then 1 to wisdom,

Also get advantage on dex saves against force abilities, and being charmed.

Also get proficiency in any 2 vibro weapons.

Plus it's a pretty rare species, you'll gave alot of freedom for your tribe and how you got offworld.