Who are they going to sue? Yotta? Synapse? Evolve?

Typically you just sue all three, which is called joinder. However this may be out of scope for small claims. Practically, banks and insurance companies seem to be immune to lawsuits, so I would put the odds of this working at very, very low, whereas if a ycombinator meal prep startup intentionally poisoned you I would expect a lawsuit to get through much more often: somewhere on the order of magnitude of half the time.

If it were me I would pick the one that I had the direct business relationship, or failing that the one that is solvent. But the strategy is specifically banking on the fact that small claims court is more favorable to individuals without legal training than other courts are, and the dollar amount isn't worth the company sending someone to fight over it.

All of them, and the founders, officers, and investors, personally?