The weaknesses of Erayo are: Disrupting the Erayo flip: Erayo flips only on the fourth spell cast on a turn, therefore the timing of playing Erayo becomes critical
Compared to shroud, which prevents a card from being targeted by any spells or abilities, hexproof allows for more interaction and involvement
You can use it to remove unfavourable blocks and, after damage has been dealt, to give a sudo vigilance to creatures
There are three main ideas that are applied to your two commanders
Skullbriar Counter Voltron Skullbriar, the Walking Grave was one of the very first decks I built when I got into Commander back in 2011
If your opponent doesn't have an answer for Bolas pretty soon after he is played, then the game is going to slip from their fingers relatively quickly