They have massively buffed Gigantamax Garbodor stats. It has around 1.6x as much attack and 1.6x as much HP compared to the "standard".
With energy bug, Crowned Shield Zamazenta has to keep using Behemoth Bash or give up dealing damage entirely while charging, which is another difficulties to this Duo.
Spirit is used to balance Crowned Shield Zamazenta HP so they can survive longer even if Garbodor keep targeting a particular one of them.
Edit: Fixed calculation mistake on Garbodor's stats
by Nikaidou_Shinku