I know that if you beat Halo MCC on legendary you will get the Helioskrill armor for halo 5 but will you still get it if you used the bandanna and scarab skull?
Certain skulls have 0.0x modifiers. There are conflicting reports on whether these types of skulls cancel out achievement tracking. I've heard people say that using Bandana and Scarab skulls prevent achievements and therefore would also prevent armor unlocks in Halo 5, but I've also heard some people say you can use them. Most reports, though, say that using such skulls prevents getting things like Helioskrill.