So, an interesting rules questions from UK players/judges that i was chatting with at the sides stage on Day 3 of Worlds:

"Can i choose 'equipment' for with PX-238 Winter Wondervolt? Because if i have 'Chipper' Ironbane in play, i should be able to destroy any ally in play, correct?"

From Paul Ross:

An “ally type” is any tag on the left side of an ally’s type line. For example, Dwarves are cards in play with the “Dwarf” ally type.

So that means "Pet" and "Unique" are out (because they appear only on the right side of type lines) as are "made up" tags (that haven't been printed on any allies yet.)

Presumably, this will be in the next Comprehensive Rules update.

This tells us that you can not choose types, such as Equipment or Ability... and you also can not choose something clever like "Non-Ally" or "Non-Resource" to get around various targeting requirements. If UDE prints a card which the Ally type of a "supertype," like Equipment or Ability, you can expect an update to the wording of cards like "Chipper" and Burn Away... but for now, you simply can not choose those types as ally types.