Arceus can't have the ability Protean??

[isleep2late]

I just tested this in the Battle Maison (after removing the banlist restrictions). Gave Arceus Protean, moved it to battle box, and when doing a rotation battle it would not change types when using a move. Thought this was a battle box thing (or maybe a rotation battle thing) but as it turns out my Arceus with the Protean ability would not change types regardless of where it battled (even tested against wild pokemon). Double-triple confirmed that Arceus did in fact have the ability Protean while in-battle.

I thought this was very suspicious and decided to test other abilities, like Wonder Guard. Sure enough, Arceus with Wonderguard is protected by non-fighting moves.... so maybe I'm going crazy, maybe I messed up my game, but the specific combination of an Arceus with Protean hacked as its ability does not work and it is making me confused lol.

 

Does anyone know anything about this, could confirm that this is in fact true, or might have an explanation as to why this is? My theory is that, just as the ability Multitype cannot work with any other pokemon, neither can Protean be used on an Arceus due to the nature of what Arceus does. Just a very rare thing... and I'm sure many people have played with Protean Arceus in Balanced Hackmons or other Hackmons formats in this game, not knowing that this could not technically be possible in the real game.

[theSLAYER]

It's like giving Forecast to Arceus.
When it comes to type changing abilities, I think they all fail on Arceus, and Castform.

Type changing abilities may work on other mons..