Well technically Rayquaza is stronger due to its higher base stat total. But Ultra Necrozma really is not that far behind as its HP, offensive, and defensive stats are just a couple points below Rayquaza’s. Interestingly enough, Ultra Necrozma is actually faster than Rayquaza, so it’s capable of landing the first move. What’s more is that Ultra Necrozma’s ability Neuroforce increases the power of super effective moves by 20%, which actually counteracts Mega Rayquaza’s Delta Stream ability which reduces the damage of super effective moves (so it pretty much evens out in terms of the amount of damage they can deal to one another). So ultimately, this fight could go either way and depends on who uses what against the other.



When you think about it, this is ultimately a challenge of Mega Evolution vs. Z-Moves (and interestingly enough, Rayquaza is actually incapable of using Z-Moves when it has Mega evolved).