Like any other stat, Evasion has 6 stages.
0 = 100%
1 = 75%
2 = 60%
3 = 50%
4 = 42.85%
5 = 37.5%
6 = 33%
So if you used it once, a move that has 100% accuracy would now hit you with a 75% accuracy.
Sadly, there are 3 moves that raise evasion.
Acupressure(raises a random stat)
Also be careful because stomp and steamroller do 2x against minimize. Double team is your best chance.
So many Pokemon can learn Double team by tm, so check Here
I once Battled Agatha in Fire Red with only Venusaur with Frenzy Plant Left. Her Gengar(last Pokemon) had used Double Team 6 times, and after using a missed Frenzy Plant 4 times, my 5th finally hit it. It was a lethal Battle.
A ground ghost type would be nice with double team to resist shock wave/swift(moves that never miss)