A male lion will beat a tiger even though the tiger will have 1/3 more body weight.
Male Lions' fight to kill, tigers won't fight. A male lion will never stop coming, a tiger will quit immediately. Male Lions exist only to kill. Tigers are hunters.
Male Lions are absolutely relentless. Do a deep dive on lions vs. tigers - look specifically for comments by animal trainers from the early 20th century.
A lion vs. a bear? That's a good question. Bears don't have an off switch either - and they have more natural defenses. I'd take a grizzly or polar but I don't know about a standard black bear.