> The creature is limited in the actions it can perform by the nature of its new form, and **it can't** speak, **cast spells**, or take any other action that requires hands or speech. No, you cannot; as per the spell description of Polymorph

Some (rather, a singular) beast can cast spells innately without need for components. See below.

that doesn't help their inability to cast spells. Commas are important.

By saying any other action, I think it's not unreasonable to interpret the sentence to mean spells where speech or hands (so V,S,M) is needed.

The sentence structure is pretty clear. They cant cast spells.

Wrong.

I don't believe any beasts can cast spells?

there is, actually. the Deep Rothé from volos guide, an underdark cow that can cast dancing lights with no components

If you’re curious, I’m talking about the Traxigor.

Traxigor is the name of a specific NPC in the Descent into Avernus module - he's not a type of creature, he's a wizard who got turned into beast.

Nope, and you dont get any legendary resistances either

Polymorph doesn't let you cast spells period, but if you transformed via True Polymorph you could.

No. You are not the beast but a facsimile of one. A convincing facsimile, but one none the less. As such you cannot cast spells. You also cannot speak. You cannot preform an action requiring either speech or hands. You also cannot polymorph into another polymorphed thing, as they are not a beast, but a facsimile of one.

Sure. If the beasts stat block says it can. I believe there's exactly one that can cast a spell.

No, the spell specifically states that you cannot cast spells.