@dexter106
What's the point of promoting weaker balls? The challenge is not centered on capturing, you might as well make it friendly for anyone. You can add stuff such as "pokeball-only", "no legendaries" as optional rules if you were worried about the game being too easy in the case of those issues.
Then why else should you use any other ball?
What's the point of these balls becoming available much later in the game?
I initially wrote the values up the same way you did, before posting it. But when I asked those same questions to myself, I immediately got an answer by turning it around. It kinda makes sense to have it this way.
Also, just to point out a case, Master balls should definitely have the highest value, no matter what. It's one-of-a-kind (well, kinda) so it really makes the player think carefully which pokemon he/she should use it with.
As for the no pokecenter, no pokemart survival challenge. Someone actually pulled it off with a Feraligatr iirc (all the way until Red). It's mostly about choosing the best starter, and making use of TMs/HMs and the move deleter. It's possible considering that you can finish the game fighting less than 100 trainers, get a ton of TMs, Ethers, and Elixirs. Now to try it on Gen1 with a Venusaur... see,
that's impossible XD
Edit: I'm currently testing the challenge I suggested, particularly for Pokemon Emerald as there are not much high-level wild pokemon to use as compared to the newer gens. Assuming that we could still get Lv3x pokemon end-game (with ultra balls, you could still reach level 5x) and a high-level Hariyama on Victory Road - not to mention that you could ask the help of the Legendaries as well! - Steven shouldn't be impossible to beat, even with his levels at 7x. Should be a great challenge to fight him at those levels, too, imo.