I was scrolling, and just thought of this. My idea of this matchup is 'Level 100 Magikarp v Level 1 Eternamax Eternatus'. I was purely curious, because Magikarp learns only tackle naturally, as far as I can remember, while Eternatus learns more powerful moves, but then, there would be the whole thing about stats and EVs and so much more that it would be interesting to see these two fight. You're free to choose your own 'worst and best' Pokemon, because it'd show how much something either sucks, if the Level 100 lost, or how much Levels affect the game, if the Level 1 lost. It'd be cool to know!!
Even if a Pokemon is considered the best, it can't win against a level one hundred Pokemon at only level one. Even if it is the worst Pokemon that is level one hundred. The level of the Pokemon plays a big difference in the outcome of the battle.
Check this out:
In this replay, I purposely made Blipbug not attack for a few turns. Even if a Pokemon has a super effective or powerful move, it would do so little. Why?
It all has to do with level and stats.
Because Eternatus was only level 1, it had horrible and such low stats. Even if it landed a Flamethrower, it wouldn't do that much because it's stats aren't the same. The lower level a Pokemon is, the lower it's stats are. Because Blipbug was level 100, it's stats were much better than Eternatus' stats. This is how a Blipbug that used Infestation, a 20 Power move, was able to knock out an Eternamax Eternatus. This would be the same for every other Pokemon. As cool as it may sounds, a level one Pokemon just doesn't have the stats to take down a level one hundred Pokemon.
Hope this helped.