Animate Guardian + Ancient Skull

"Ancient Skull"
https://www.poewiki.net/wiki/Ancient_Skull

"Animate Guardian"
https://www.poewiki.net/wiki/Animate_Guardian

"Summon Phantasm Support"
https://www.poewiki.net/wiki/Summon_Phantasm_Support


If I Animate Guardian wearing "Ancient Skull", would those modifiers as;

"Minions have (40-20)% reduced maximum Life"
"Minions have (15-25)% increased Movement Speed"
"Minions have 50% increased Critical Strike Chance per Maximum Power Charge you have"
"Minions can hear the whispers for 5 seconds after they deal a Critical Strike"

work for my other minions? or just for the Guardian? would it work for "phantasms" summoned by a "Summon Phantasm Support" linked to the Guardian?

I suspect it wouldn't apply to your minions, but you can easily do some testing since the helmet is so cheap. Look for them degenning to the chaos damage.

I'm upgrading a gem "animate guardian" for the test

suppose it works, could i stack "ancient skull" modifiers if I and the guardian wear one each?

if yes, it would be very easy to stack critical chance with "host chieften spectre"

It would apply to your AG's minions if ag wears one. But not your minions