Lucía is a Mii from the Wii.
Lucía originally appeared as one of the 60 CPU Miis to be included with Wii Sports. Since then, she's appeared in Wii Sports, Wii Sports Resort, Wii Party, Wii Music, Wii Fit, Wii Fit Plus, and Wii Fit U. In most of these games, her internal ID is 059, however in Wii Music it is 24. Her Mii data filename is cpu_mii_059.rcd in Wii Sports, mii_059.rsd in Wii Sports Resort, Wii Fit, and Wii Fit Plus, mii_059.ffsd in Wii Fit U, and is cpu_mii_db24.rsd in Wii Music. Wii Party combines all 100 Mii data files into one larger file named mii_rsd.bin in the same ordering as Wii Sports Resort.
As with every CPU Mii, she has Mingling turned off. Her Mii name in her Mii data file is ルシーア. In her Wii U/3DS-format Mii data file, she was originally created on a Wii (1).
Her Mii data file contains unused data. Her glasses are set to be brown (Wii glasses color row 1 column 2) and moved 5 down.
In Wii Music, her Mii data file is slightly different. While it's mostly the same as it is in Wii Sports Resort, it now includes a filled out Mii ID and console ID. Her Mii ID is 80-4e-9d-be and her console ID is c2-3d-21-af. Her Mii ID tells us she was created on August 27, 2006 at 12:39:20 PM.
According to a September 2020 Nintendo leak about CPU Miis, Lucía's nationality is Spanish (Spain).
In the files for Wii Sports, her dominant arm for Baseball (Batting) is right-handed, Baseball (Pitching) is right-handed, and Tennis is right-handed. Her unused dominant arm for Boxing is right-handed. Her Baseball Pitching style is normal. She's ranked 38 in Baseball, 47 in Boxing (meaning she doesn't appear in Boxing), and 50 in Tennis. Her group IDs are 9, 2, and 1.
In the files for Wii Sports Resort, her Wii country ID is 1, like all CPU Miis. Her dominant arm for Table Tennis is left-handed. She's ranked 69 in Swordplay, 68 in Basketball, 0 in Table Tennis (the best), and 8 in Cycling. Her unused Canoe and Debug ranks are both 59, matching her ID value of 059.
The PAL version of Wii Sports Resort contains a small bit of lore mentioning the relationship Lucía has between her and Yoshi (Wii). It describes that Yoshi was Lucía's previous mentor, who she quickly surpassed. Here is an excerpt of the final stamp's description in the EU English localization of the text:
Defeat the Champion
Beat the table tennis champion
in a match.
The current champion quickly
surpassed her teacher Yoshi,
and has since gone undefeated.
Lucía appears in promo art for Wii Party playing Popgun Posse.
Names in other languages
Source: Wii Sports Resort
Note that fans may stylize her name as simply Lucia.