yeah that's actually impossible, "your" cresselia takes only 36% max from a neutral metagross's meteor mash, which it had to be if it was able to outspeed cresselia on turn two. metagross is either 90 or 99 speed, and even though 90 speed could indicate the 16% chance that metagross is +Atk, it definitely means cress outspeeds it on turn two for the thunder wave since 90 speed means 135 with a scarf and cress is 137.
further, cress only takes 39.65% max from +atk MM anyway which means that even after a boost metagross isn't killing cress without a CH, so you definitely missed or forgot about a CH there or something, even though a -Atk CH MM does 54% min and puts you in the yellow and definitely not at a visible "45%". so that said there's no way meta was +Atk since it outsped you on turn two, and more importantly there's no way it didn't get a CH on turn two...at any rate and if meta got you with an Atk raise MM on turn 1 and was actually +Spe and then CHed on turn 2 (i'll ignore the turn two attack raise) you fell victim to 0.17% hax which is pretty lol, but you definitely got Ched one of those turns