I remember making that RMT a long time ago about an OU team I had made with Jynx in Rain, and it was amazing. Jynx ended up being the MVP in over half the matches. All I needed was for Lovely Kiss to actually hit late game and it was smooth sailing from there.

Jynx @ Leftovers
Trait: Dry Skin
EVs: 252 SAtk / 4 SDef / 252 Spd
Timid Nature
-Lovely Kiss
-Substitute
-Nasty Plot
-Ice Beam

Play smart with this thing in Rain and it just never dies. Seriously. You get 3/16 of your health back every turn, so it's easy to stall out dangerous moves such as Ferrothorn's Gyro Ball and Terrakion's Stone Edge / Close Combat just by spamming Substitute. Once you get a Nasty Plot or two, go to town with Ice Beam. It's amazing just how strong Jynx can get with some Nasty Plot boosts. Even offensive Heatran is easily 3HKO'd at +6 by a move it 4x resists, and Jynx even has a shot at 2HKOing it if it has taken any significant damage over the course of the match. So yeah, try this thing out. For real.