The other XYZ monster, while less often summoned, has the ability to send a card from your opponents hand to the graveyard, and those cards are always considered extremely good
With the new pendulum monsters from structure Deck: order of the spellcasters, you don't have to worry about playing your monsters as spells because they all have effects that summon themselves from your pendulum zones
Tidal would also remain at 3 in Atlantean Mermail lists while it was allowed, as making Rank 7s was a strong part of the Atlantean Mermail strategy, plus Tidal still triggers Atlantean effects
This is because Selene can re-set itself from the GY which is key in some scenarios
Monarchs were all about tribute summoning which would then allow them to use their powerful effects when they were summoned
His stats are unsuitable for his level, and even if he destroys everything, he can easily rebuild his deck