Should I add a zombie? Cause, I'm pretty sure most people could at least take out a zombie...
Anyone that has done tameshigiri knows that it is designed to mimic cutting through actual bone and flesh. I am assuming the sword should be a 5 body ryu guruma, not some crappy fake blade.
Elephant: It is just as likely that I would die as it is that I would win. Even if I can cut through green bamboo and a tami mat, an elephant has very thick bones and very thick muscle, so it would be incredibly difficult and I am not so strong that I think I could take one out. I think the only chance would be to kneecap it and finish it off after it collapses under its own weight. It's unlikely one would be able to take out an entire leg of that density, but it would be possible to cause sufficient injury to make the beast collapse under its own massive weight. I would imagine one would want to do this in motion to avoid being crushed, since the elephant wouldn't just magically stop so soon before succumbing to its own weight. You'd need to either take it from the side or move in such a way to avoid getting trampled or whacked by the trunk. Trampling could kill you and the trunk would be enough to knock you back several yards and maybe unconscious... then it's likely it would come crush you. But, if you could manage to take out a knee and make it collapse, you have more or less won. An elephant skull is very thick, but if you've disabled it enough that you can move around much more agile than the elephant, then it would be not so difficult to further disable and kill it. Overall, if it was charging, even having studied swordsmanship for years... I'd say I'd have a far greater chance of dying than living.
Bear: Maybe. If it was enraged and charging then probably little chance of survival. The only real chance would be to get a fatal first strike. The bear's charge would be its own worst disadvantage. A human's own strength would render it difficult to cut through a bear's thick muscle and bone, but with the force and strength of a bear behind the blade, then you would have a very good chance of clean penetration. With a charge, if you manage to aim correctly as it comes at you with an overwhelming power, then you'll likely live. But if you don't get the fatal blow at that one chance, then you're done. Fortunately, it's unlikely the bear would live very long after the encounter with the blade piercing its entire body. Hopefully you will have at least damaged something vital, though without an instant kill, you will die regardless.
In turn, I think I would have a decent chance against a bear under normal circumstances with a katana. I am assuming it's aggressive, but trying to intimidate by going into a standing position, roaring and whatnot. It leaves itself very vulnerable in such a situation, but it is instinct and it does not understand such things. It's likely I could get a first strike and that's all it would take. If not, using the bear's own strength of its swings when it tries to maul, it would be entirely possible to dismember it. I doubt someone untrained would have much of a chance, but... I think I'd have a higher chance of surviving than not against a bear, assuming it's not charging. At the very least, the bear wouldn't live longer than a few days after the encounter unless I happened to be very unlucky and got caught off guard, in which case I could probably die in a single swipe. Not so much from the 5 inch claws, but the power behind the hit would be enough to snap my spine in two. I think I could do it though...
Lion pride: Not a snowflake's chance in hell. A lion is about as big as a horse (if you've never seen one up close, they're HUGE). One on one, I'd have less chance of survival than fighting a bear. But, I'd say it's doable... not easy, and not without scars, but probably doable.... An entire pride though, no way. I might be able to at least mortally wound one or two, but if the pride even had just one more lioness then I really doubt it. The chances go down exponentially as their numbers increase. If they came from the front one at a time, then I'd have a somewhat decent chance of survival, but since they're intelligent hunters, it's far more likely they'd come more than one at a time and from multiple directions. Since lions actually jump and overpower their prey with their entire weight, even getting off a fatal strike on one would prove fatal because the power behind their attack would knock you to the ground at the very least and once that happens you're as good as dead because then the others would come in for the kill. So yeah... against an entire pride, zero to no chance.
