I just wrote the blog post on how I would classify the traditional tetralogies if I took them all as genuine as Catherine Zuckert did.
From the current perspective though, after so much scholarly work doubting the provenance of many dialogues, it is hard to derive an interpretation based on works mostly considered dubious or spurious. Taking into account the modern judgment on authenticity, this is how I would classify the Platonic Corpus or 45 works, again with Octalogies and tetralogies.
Group I - Socrates' last year / Trial and Death:
8 works: Apology, Crito, Phaedo, Euthyphro, Cratylus, Theaetetus, Sophist, Stateman
Group II: Theoretical Debates / Poets and Politics:
8 works (not yet in order): Laws, Parmenides, Symposium, Phaedrus, Philebus, Republic, Timaeus, Critias
Group III: Socratic Practice / Sophists and Citizens:
8 works (not yet in order): Protagoras, Gorgias, Hippias minor, Charmides, Laches, Ethydemus, Lysis, Meno
These 3 groups totalling 24 works - the authenticity of these works have not been in doubt either in antiquity or in modern times. Clearly the core of the Platonic Corpus
Group IV: Needs to reference
4 works: Menexenus (for Group I), Ion (for Group II), Hippias Major (for Group III), Letters.
The first 3 works current scholarship inclines towards considering them authentic. Letters most consider spurious but if one wants to understand the Platonic Corpus one has to be familiar with at least what is said in the 7th letter.
Group V: Dubious / Spurious per modern scholarship
8 works: Alcibiades I, II, Clitophon, Theages, Minos, Hipparchus, Rival Lovers, Epinomis
Group VI: Considered Spurious since antiquity
8 works: Definitions, On Justice, On Virtue, Domodocus, Sisyphus, Halcyon, Eryxias, Axiochus (not included in the traditional 9 tetralogies)
Plus Epigrams - which no one consider key to understanding Plato even if they are all authentic.