How did Mega Sableye use two abilities at once?

Question

So I was battling with a friend and I used my mega sableye,which has prankster.When the battle started I started with sableye and mega evolved.For some reason however I used will-o-wisp first on the opposing gliscor and when gliscor used stealth rock sableye bounced the move back,which means that both prankster and magic bounce came into effect while sableye was mega.Is this a glitch about the ability change that occurs on the first turn of mega evolution?

Answer 1

>Performing Mega Evolution will not alter the turn order, so a Pokémon with a lower Speed than their opponent will still go after them on the one turn the Mega Evolution occurs, even if their Mega Evolution increases Speed and would otherwise cause them to go first. The opposite is also true for Pokémon who lose Speed from Mega Evolution, such as Garchomp. However, turn order will be determined normally on every turn afterwards.

Same with abilities like prankster. That's why mega Sableye is the best mega of all time.
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