Marts should be charitable

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Upon talking to the salesman in a Mart, the player should be given 5 free Pokeballs and a pep talk if the following conditions are met:

• Only one Pokemon in the party
• Too poor to buy balls ( < 200 pokeyen)
• No Master/Ultra/Great/Poke balls in the bag or PC
• No Pokemon in any of the PC boxes
• The party's lead (only) Pokemon has no damaging moves

In Cinnabar Island's Mart, the game should also check if you've picked up the Good Rod. If not, the Mart should give it to you.

This will prevent any softlocks caused by losing all Pokemon except for one with no attacking moves and being too poor to buy Balls to catch something else. This situation is otherwise impossible to get out of, because no trainers can be beaten to earn cash.
Cinnabar is especially heinous, because you can't leave without Surf or Fly, and none of the Pokemon in Pokemon Mansion (the only available wild area on Cinnabar Island) can learn those. The Good Rod can catch Goldeen and Poliwag, both of which can learn Surf.

[chaos-lord]

Only one Pokemon in the party
No Pokemon in any of the PC boxes

There's theoretically nothing stopping you from having multiple cocoons
Also, this could trigger very early in the game if the player dies enough on route 1 to be poor as the other 3 conditions would be met, not sure if you care about that. A quick moves check to make sure there's no damaging non-sacrificial moves in the party might be an option but leaves room for bugs.

[aaaaaa123456789]

If you have multiple cocoons, you can release them.

[m4-used-rollout]

Checking for the remaining Pokemon having all moves with 0 base power should be doable.

[m4-used-rollout]

Another thought about Cinnabar: Instead of having the Mart attendant give you a Good Rod, we could have the lab spontaneously regenerate the fossil mon you chose if the one you revived gets released. Both the Omanyte and Kabuto lines can learn Surf.

[m4-used-rollout]

Stranded on Cinnabar is now its own issue (#23)