Oh that's me! I'll go through what I know for all the stages.
Normal- Hopefully you can figure this out for yourself. The platforms are at a really good height for you to abuse. In general it's a really long stage, so if you control the center/push your opponent towards the edge, you'll live pretty long.
Ground- Check out that Cubone. If both you and your opponent are fighting on the left side of the stage, your down-b goes up and down the slope really well, it actually gets a range boost because of the slope. If you fastfall into the slope with an aerial, or just fast fall into it, you'll get a significant slide down it, making some aerials safer. If you're on the left, and he's on the right, your best option is probably to just wait it out. If you want to stay aggressive, you'll want to get around the opponent and get on his right, use the platforms to keep out of reach. If you're on the right and he's on the left, your u-tilt and b-air can hit through the ground if he's too close. Otherwise, just go to the right and pester him with down-b or whatever. If you're both on the right, you probably want to be on the right side of him to abuse the wall; even if you don't infinite you can do some pretty sweet combos off it.
Electric- Preferably, you want to control the center here. Stronger attacks like giant punch and f-smash can knock a shielding opponent onto the treadmills if they're shield camping there. When you're in the center, just watch your opponent and react, keep them from approaching. When you're on the sides, it's not as bad as you'd think. Pretty much everything you do can become relatively safe when you're on the treadmills, because the treadmill carries you away during your lag. You can even approach with f-air if you want, but that's still stupid. Running up and down-bing is good, so is running up and giant punching. If you want, you can up-b through the middle and make it to the opposite treadmill for safety if it doesn't work out.
Ice- Simply, don't move much. We're already huge enough to reach our opponent mostly wherever they are. It'll be harder for the opponent to get in your range if you stay still. Air game isn't effected by the ice, so feel free to use that normally. Oh, and down-b is awesome here too. When your opponent starts moving in a direction, they pretty much have to commit to that, so you can punish that with down-b.
Flying- Stay grounded! DK's fallspeed is actually pretty lame. Obviously down-b is great here, since they can't punish it by jumping generally, they'd jump up too high and you could stop in time. If you're fighting someone with less fallspeed than you, you can try and jump and juggle them or hit them and you'll be alright generally. If you're fighting someone with more fallspeed than you, never jump unless you're sure you'll hit them. Just try and stay on the ground and punish their landing, you're big and scary. They'll make a mistake generally, like airdodging too early.
Characters you shouldn't take to PS2: MK, GW, Marth, ZSS, Fox. Should be mostly obvious why.
Characters you should take to PS2: Olimar(every stage messes up his pikmin, they get lost/disconnected), Ice Climbers(Nana is dumber than pikmin, transforming stages break grabs), Luigi(Ice, air, and electric RUIN him).
For everyone else, the most important thing is personal experience. If you're facing someone who doesn't know this stage, and you know how to play the stage, you might want to think about taking him here. Just play the stage a lot, it'll come to you eventually.
Edit: PFFFT just read that this is the "Simple Questions & Answers Thread". Short version: Use down-b a lot, be experienced at it.
Some of my biggest threats as players are most likely going to be a Falco main, a MK main, a Diddy main, a Olimar player, a DDD main (the player alone makes this MU 90-10. He's just too good) and a Pika main. 
