The lowest level wild Pokemon is 2. Of the Pokemon that can be found at level 2, the one with the least physical defense is Hoothoot.
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A Shuckle that does 1 damage to this Hoothoot with constrict must be at most level 7, even if the Shuckle has no IVs or EVs and the RNG always rolls as low as possible.
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If you don't want to use false swipe, the next fastest way to lower a wild Pokemon's HP is most likely direct damage. The most reliable direct damage moves are sonic boom, seismic toss, night shade, and maybe also super fang.
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Another thing you can use is sandstorm, or some other status that does fractional damage.
If you have too much free time and nothing to do with it, you can try playing other video games, joining a club or sports team, or getting a job. If you think there are too many games and you can't decide which ones to play, I personally recommend games from this list, this list, or part 2 of this list. If you want a job, it's often easier to get hired (at least in my country) if you know someone who works where you're applying. You can try asking around to see if any of your acquaintances' companies are hiring.