Also according to the official Nintendo Player's Guide for Collector's Edition, the English names for Fokka and Fokkeru are "Eagle Knight" and "Soprano," respectively.

I know >_>
I'm saying they're a substitute that has a different name but is otherwise identical for all practical purposes.
Stalfos->Stalfon (called Stalfos in Western manual, then Stalfos Knight/Skeleton Knight in later games)
Tartnuc (Darknut)->Ironnuc (Iron Knuckle)
Wizzrobe->Wizzuzar(?) (Wizard)

Though Carrock seems to be a Wizzrobe.

Anyways, the best reason I can think of is that the palace enemies work for the Royal Family instead of Ganon, like the overworld/cave enemies do. Note how overworld/cave enemies like Moblin/Molblin, Goriya, and Zora/Zola are reused wholesale from the first game, though with some added new ones like Daira and Geeru that don't really match up with a "The Hyrule Fantasy" enemy. The only Palace enemies that are also in the first game are Bubble (which was treated more as an obstacle at this point) and the JP version having blue Octoroks in one dungeon.

Ironknuckles were technically Ironnuc and I think the wizard did have name similar to Wizzrobe but not actually it.

EDIT: ウィズザール The first part is the same as Wizzrobe, the latter I'm not sure how to translate.

@MisterMike Which was translated by the incompetent Dark Horse, as shown by all the problems especially prominent with their overuse of fan wikis for Zelda Encyclopedia and Super Mario Encyclopedia. Suffice it to say, it's a far cry from a "reliable source."

Anyways, "Stalfon" is ostensibly the same as Stalfos Knight according to JP name, probably a similar situation to how Ironknuckles and Wizards are essentially an identical replacement to Darknuts and Wizzrobes, respectively.

@Doc von Schmeltwick
Ohh, good catch! I didn't even notice that they were called that.
The "Stalfos Knights" being called "Parutamu", on the other hand, is accurate according to the Arts & Artifacts book. Naturally, this is a romanization of their Japanese name "パルタム (Parutamu)", a name which doesn't seem to match with the one used for Stalfos Knights "スタルフォン (Sutarufon)" circa Link to the Past, which is ironically also used as the Japanese name for the standard Stalfos enemy in this game, rather than Stalfos "スタルフォス (Sutarufosu)" like in the first game.
I'm still in agreement that it should've been called a Stalfos Knight, though. :/

Very minor thing:
The Iron Knuckles are technically "Ironknuckles" in this game. If the later name is used, "Stalfos" should probably be "Stalfos Knight," since that's it's later name (as it is in fact different from the things just called "Stalfos" in the other games).