American Plant knocked Uzcategui down twice as he dominated the early rounds then faded over the last few but managed to hold on for the crown at the Microsoft Theater in Los Angeles.
Kom capped her 2018 campaign with her sixth world championship title after defeating Ukraine's Hanna Okhota by 5-0 in Delhi.
Mayweather floored Nasukawa, a kickboxer less than half his age, three times in the first round of the three-round contest before the Japanese fighter's trainer rushed in to stop the fight.
The 41-year-old unbeaten champion has been tempted out of retirement -- again -- for a one-off "exhibition" in Saitama, north of Tokyo, against "Ninja Boy" Nasukawa, a fighter more than half his age at 20.
Warrington won a unanimous decision by two scores of 116-112 and one of 116-113 in the first defence of his world title as he extended his unbeaten professional record to 27-0.
Stevenson has not improved since doctors sedated him and put him on a medical ventilator to breathe after his 11th-round knockout loss to Ukraine's Oleksandr Gvozdyk on December 1 in Quebec City.
A car, pickup trucks and appliances were raffled off and President Rodrigo Duterte and celebrities were among the well-wishers at the all-night event, held at a sprawling shopping mall in his home city of General Santos.
The New Year's Eve bout, first announced in early November, was abruptly scrapped by the unbeaten 41-year-old American after a "misunderstanding" over the fight's terms, according to mixed martial arts promoter RIZIN.
The Mexican was competing in only his second fight since completing a six-month ban for testing positive for a banned substance in March.
Upon announcing the investigation the IOC suspended qualifying for the 2020 boxing tournament -- making it the only sport not to have its qualifiers approved -- and warned that it could be stripped of the right to run the competition.
American Wilder retained his WBC belt after a thrilling 12-round battle ended in a split decision draw.
The 33-year-old Singh, a bronze medallist at the 2008 Beijing Olympics, has an unbeaten 10-0 record since he turned pro in 2015, but failed to get a single fight this year.
Adonis Stevenson's doctor Alexis Turgeon said it was "too early to comment" on the fighter's long-term prognosis, but it was likely he would have lasting neurological damage.
The Haitian-born boxer, 41, was admitted to the hospital on Saturday after the unbeaten 31-year-old Gvozdyk finished him off with a crushing right hand.
Stevenson was dominated almost from beginning to end by Gvozdyk, who sent the Canadian champion reeling before landing his knockout blow in the 11th.