Munkidori is probably the best one but still had faults like being forced to use Focus Blast and sharing same speed as Enamorus.
Okidogi is solid too, but held back by Sneasler being the better Fighting/Poison type, even if Okidogi checks it and has moves Sneasler would kill for. It’s also slow, slower than Great Tusk which typically is bad thing for Poison types, unless you have regenerator.
Fezandipiti is definitely the worst by a long shot.
It’s stats are fine, but its movepool is absolute garbage. It has a total of 3 things to “threaten” stats what so ever (including status moves), and only 1 way to beat Poison what so ever. Being Double Kick, Heatwave, and Tera Blast. With Fezan unable to touch 2 whole types what so ever, Fezandipiti lets them in for free to do what ever they want.
For reference, even with full investment and neutral nature, Fezandipiti only OHKOs Scizor with Heatwave about 80% of the time and fails to OHKO Scizor without investment. It also fails to OHKO Offensive Kingambit with Double Kick, even when using Technician.
If Fezandipiti got at least one of T-spikes, spikes, stealth rock, knock off, hypnosis, thunder wave, will-o-wisp, etc, it might have a small niche since then it could actually have something to do against most Steel types and Poison types.
Keep in mind it also has issues with Gliscor, Garg, and even Clefable if it isn’t running physical poison moves, and most physical attackers in general can usually just hit hard anyways.