1) 85kg vietnamise domestic pig vs 20kg caracal
2) 100kg red river hog vs 35kg euroasian lynx (stealth)
3) 100kg red river hog vs 65kg leopard
Vietnamese domestic pig (85kg) vs caracal (20kg): The Vietnamese domestic pig (also called the pot-bellied pig) is a compactly-built suid that is rotund and deceptively heavy. One of the zoos I visit on occasion has a collection of these pigs, and visitors can throw corn in their pen to feed them. The larger ones seem greedy & aggressive at feeding time, and will bully the smaller ones out of the way (at times delivering quick bites) to get what they want. Many Vietnamese domestic pigs have their tusks trimmed, but they are certainly present (and can grow quite long) and can be good weapons. Caracals are lynx-like felids with great athleticism and quickness. They usually predate upon small animals (rodents, hyraxes, hares, etc.), but can take young antelopes. The pig's thick, loose skin won't be easy to breach with claws & jaws, and the caracal's attempt to do this against an animal over 4 times its own weight will put it at risk of being injured by the pig's offense. The Vietnamese domestic pig may not be as formidable (or quick) for its size as a typical wild pig will be, but it will still be too tough for the caracal to deal with on most occasions. Vietnamese pig wins.
red river hog (100kg) vs Eurasian lynx (35kg) by stealth: The red river hog is a reddish-colored suid that has long ears and short, sharp tusks. Red river hogs are very social animals, and occasionally congregate in large groups. The Eurasian lynx is the largest of all lynxes, and is a very capable hunter. It has great agility, speed, weaponry (jaws & claws) and killing know-how. The Eurasian lynx typically predates upon small to medium-sized ungulates, and wild boar are sometimes on the menu. Although the lynx is capable of successfully ambushing animals larger than itself, a suid weighing almost 3 times as much as it does will be a tough challenge. Many predator/prey encounters start with an ambush, but when the ambush is not successful, the encounter turns into a face-to-face battle. A lynx won't be able to easily ambush an animal this large, and will be in trouble if the red river hog turns to face it. It's not impossible for the lynx to pull this off, but it won't succeed on most occasions. Red river hog wins.
red river hog (100kg) vs leopard (65kg): The red river hog population has steadily increased in some areas, likely due to the reduction in the leopard population. Leopards are among the strongest felids pound-for-pound (it is generally accepted that it is second only to the jaguar), and are very accomplished predators. These cats have amazing agility & power, and have very developed shoulder muscles that enable them to drag large prey items high into the trees. Leopards deal with suids on occasion (including warthogs and the red river hog), and know how dangerous they can be. The leopard will need to use its quickness and agility to avoid the slashing tusks of the red river hog (which won't be easy because most suids have good lateral mobility), and seize it with its claws in such a way to arrest the movement of the anterior portion of the hog's body while enabling it to position itself for a killing bite (typically the throat). Any big cat will find this challenging against a suid close to its own weight, and will find it very difficult against a suid weighing 50% more than it does. The leopard will have a chance to prevail with an ambush, but won't be the animal pressing the issue here in a face-to-face encounter. The larger red river hog will repel the leopard more times than not. Red river hog wins.