I think the biggest thing Rain teaches you is to be smooth. Nothing breaks traction in the rain like snappy inputs. In the dry, you can get away with quick turn in or slamming the throttle down as the grip levels will forgive you. In the rain, if you turn the steering too quickly the front end will push and if you apply throttle too quickly off the corners, the rear will step out. Its like you have to slow everything down to go fast. You start turning in earlier at a slower rate to hold the grip. On exit, you put down just enough power to drive out of the corner with out sliding. These are all principles good drivers talk about in the dry. I imagine the affects those principles are merely exaggerated by the low grip conditions of the wet. I suspect Great Drivers have learned the to better read the limits of grip and hold their vehicles right up against those limits.
Racing in the rain with slicks really teaches you to be smooth, especially with a shifter kart!
I mean depending the track I think you are getting way ahead of yourself for 206. As I said in the other thread. You said you had 20 minutes. You’re not going to be changing clutch springs in 20 minutes along with everything else.
Im on a 219 chain and jump 2-5 teeth on the rear gear. Push the rear hubs in to as narrow as I can go. Put on the filter cover. Toss a foam pad in the bottom of the seat. Slap on some rains and send it. If you have more time then you can look at front end alignment changes pending how it felt in the first session.
I agree with Lindsay, if you only have 20 min, make sure you get the chassis settings he mentioned figured out. Widen the front, narrow the rear, sit on something to simulate a raised seat, and if you have time, change gear and go up a few teeth.
I disagree slightly with Greg regarding the driving aspects of rain. It isn’t necessarily all about smoothness, though you do have to have a very acute feeling for the grip limit. @Terence_Dove’s old lessons on rain driving from Karting1 is how I try to do it. Big input at the beginning of the corner, charge the corner, get the kart to jack, and then smoothly modulate all inputs through the corner to keep the kart from breaking free. I’ve posted this pic a dozen times on this forum, but it shows what I mean:
Really need to use your body weight in the rain.
Thank you all for help…
I think gear manners less than some other things. You will usually have enough power to spin tires in rain. More is not needed. I think equalizer comes mostly because the fast guy has brake, apex, and throttle point dialed in for dry track. In rain it changes lap by lap tending to bring the less consistent more on line with more consistent since everyone is not going to be consistent.
I’d say it depends on the track. With rain corner speeds are going to come down. Which means optimal rpm is going to be affected. This is in regards to 206. More horsepower classes I would agree it might not be as critical.
Ha Ha! Remember the Axle Thread…I don’t have a problem getting the kart to Jack in the Corners. My issue is too much inside wheel lift. Maybe that’s why I keep up better in the Rain. 
Thought it apropos.
Guys, thank for all good comments and hints - this is all so helpful. Appreciate all!