Feedback: I'm biased because I won, but I had a great time. This was very approachable even for a complete beginner, while still having sneaky hidden tricks.
I legitimately did not expect to do that well.
If I have done better than others, it is because I have stood on the shoulders of, uh, ogres at least.
I've gotten two morals from this. The good moral is 'Even if you have no idea what is going on, you can still data science at something.'
The bad moral is 'When in doubt, crib other people's notes (only be sure always to call it please 'research').'
Listed in my first post, along with an updated regular team. Sorry, I should have been more clear.
Okay, I refined my approach somewhat.
I decided to search by pairs or triads of players in the opposing team, rather than just individual fighters (because that might have me selecting the overall strongest team, not a tailored one).
Using pairs, the first-level solution is in fact the same (Blaze Boy, Greenery Giant, Nullifying Nightmare, Rock-n-Roll Ranger, Tidehollow Tyrant). However, when I iterate this, I find something odd.
Nightmare is replaced by Landslide Lord.
Now, this is odd, since Nightmare is great, but a possible solution is revealed by @Maxwell Peterson's awesome analysis. Against specific (strong) characters, the Nightmare falls off. The NPC team includes only 2 or 3 of these, so Nightmare is still good, but my anti-NPC team contains 4-ish, so the Nightmare is countered.
I realize this is rather unsporting, but if possible I'd like to change my PvP team to the new combination, as it seems likely that most PvP teams will be fairly strong.
When I attempted to search by triads, I somehow emerged with the impossible result that the only winning fighter was Warrior of Winter. Still searching for the bug. Caught the mistake.
By triads, my first level solution loses Nightmare for Landslide Lord, and Tidehollow Tyrant for Phoenix Paladin. I don't know how much I trust this, since elemental balance has seemed important, but someone already submitted the team I was using so let's be different!
My new chosen team to beat the NPCs is Greenery Giant, Rock-n-Roll Ranger, Blaze Boy, Phoenix Paladin, Landslide Lord.
Iterating this is much more interesting. We bounce around between elementally balanced teams (Tidehollow Tyrant, Greenery Giant, Landslide Lord, Blaze Boy, Arch-Alligator), and teams with nothing but 5 earth-types. Nightmare is nowhere to be seen, suggesting that cutting it from PvP is almost certainly correct.
Reassuringly, the end result of this iteration is the same as that of the pair search above, so I'm confident this is a good PvP team. Amusingly, I think the earth-focused elementally balanced team the NPCs went with is the correct PvP choice; they just didn't get it quite right.
Man, it’s hard to say “check your work” without being rude. I understood about half of what you said, so your analysis was almost certainly better than my very basic one. But according to my basic analysis you’ve submitted an elementally imbalanced team which manages to also be weak. Um, no offense. Sorry. It’s just I’d want someone to correct me if I looked wrong.
Further analysis does seem to support this. Although Oil Ooze does as badly against fire as against water.
Some kind of rock-paper-scissors does seem likely.
5 watery fighters as an input team causes my program to output a team that loses Blaze Boy in favor of Quartz Questant. 5 earthy fighters loses Tidehollow Tyrant in favor of Phoenix Paladin.5 fiery fighters loses Blaze Boy in favor of Warrior of Winter.
That last one is strange. I'd expect to lose Greenery Giant there. I guess he's just that strong? Or fire is kind of bad? (Or, I have been cunningly tricked because I am bad at this).
The NPC team looks like 3 earth 1 fire 1 water. So normally you'd want more fire to deal with this. But fire is bad, so instead we bring in two strong neutral(?) fighters, the Nightmare, which just seems awesome, and the Rock'n'Roll Ranger, which is still pretty good.
Balanced teams seem important, so cutting any of our 3 strong elemental heroes seems like a bad idea. It's possible the weaker untyped hero should be swapped out for a strong fiery hero; that is, Rock'n'Roll Ranger swapped out for Phoenix Paladin, which is... also a team someone has already submitted.
I think I've made a mistake guessing elements. Because I count 6 water, 5 earth, 5 fire, and 3 neutral. I'd expect 5,5,5,4. Maybe it's 6,6,6,1?
Oil Ooze is what, pollution? Poison? Could be earth? I guess? I'm picturing Hexxus from Ferngully, honestly.
Rock'n'Roll Ranger - um, sonic?, although I guess rangers are nature associated so it could be earth again (maybe)?
Nullifying Nightmare - uh, dreams? If there is only one neutral fighter, it's probably this one.
Man, maybe one of the watery fighters isn't water? Probably the Siren Sorceress as another sonic?
Or maybe the elements are just uneven and I'm reading way too much into this.
Never tried one of these before. I have no idea what I'm doing so we'll see how it goes!
I swear I did the working on my own, but I am producing exactly the same team as another player. I guess that's a good sign?
I've edited my teams based on newer analysis. If this is cheating, just use the old ones!
Regular team:
Blaze Boy, Greenery Giant, Nullifying Nightmare, Rock-n-Roll Ranger, Tidehollow Tyrant
Blaze Boy, Greenery Giant, Landslide Lord, Rock-n-Roll Ranger, Phoenix Paladin
How I got it:
I looked at each champion's win-rate against every other champion. Then I took the 5 champions on their team and looked which champions had the highest mean winrate against all champions on the opponent's team.
Coincidentally, there are exactly 5 champions that have a >50% winrate by this criterion. So I'm bringing all 5 of them as my team.
PvP team:
The same as my regular team, embarrassingly enough.
Greenery Giant, Rock-n-Roll Ranger, Landslide Lord, Blaze Boy, Tidehollow Tyrant
How I got it:
I decided to iterate the process I used to beat the opponent's team. And discovered that the 5 best champions against that team were, in fact, that team.
I feel like this shouldn't happen. Maybe I'll look more at this tomorrow and change my mind.
I'm perfectly happy not to claim any sort of prize.
I only got the elements due to Measure.
I only dropped the Nightmare due to Maxwell Peterson.
Also, I have no idea what I'd even ask for as a scenario.