I happen to have a love / hate relationship with ladder decay rofl. You basically just wait until you have a reasonably low ranking without losing your place, and then you just battle and hope you win all the battles to remove the decay, while getting matches like +7 instead of +2 :).
And bs did you harness shakeitup's powers of something because that team is dumb lol. I'll have to use like, lum berry hitmonchan to beat it or something lmao.