Time to do math! :D
Rock Slide has 90% accuracy, meaning it has a 10% chance to evade.
Play Rough also has a 90% accuracy, meaning it also has a 10% chance to evade.
Let's run this through now. Let 10% be a .1 chance, and you have:
0.1 x 0.1 x 0.1 = 0.001%
This is due to probability. Say you use /dice 10 on PS!, which picks a random number between one and ten. With each time you use the command, the chance of picking the same number decreases. Let's let 10 be the instance where the moves miss, and 1-9 be where it hits.
/dice 10: 1 2 3 4 5 6 7 8 9 10 (10% chance)
/dice 10: 1 2 3 4 5 6 7 8 9 10 (10% x 10% chance)
/dice 10: 1 2 3 4 5 6 7 8 9 10 (10% x 10% x 10% chance)
/dice 10: 1 2 3 4 5 6 7 8 9 10 (It hits (picking a different number) so the consecutive chance resets to 10%)
