I only played the Wii version a few times, and I say it's about the same. You'll get a few "teleporting" players because of lag, but otherwise it's the same old thing. Just watch out for people who spam Maka Wuhu because of the shortcut glitch. You will eventually encounter one that will spam it over and over.
As for three stars, no one knows the exact requirements, but there are some things you should do just to be safe:
-Get first place. Not getting 1st in all races automatically equals two stars or less.
-Try to stay in 1st during races. You will get blue-shelled, so just do your best to separate yourself from the CPUs. If you are going to take a hit, brake before you travel over pits/glide areas. The time you waste falling will not help you.
-Use items wisely. ALWAYS equip an item behind you and have one in reserve, because the 2nd place CPU will almost always get Red Shells. If you get a Banana Bunch, equip them and keep an item in reserve and don't use anything...you are pretty much set. If you have Super Leaf, you may want to waste it for better items. Just weigh your options and be smart.
-Try to get as many coins as possible. 40 coins is not required, but try to keep as many as you can.
-Don't fall into pits. While falling off does not automatically disqualify you from getting three stars, don't fall in anyways.
The CPUs are practically snipers with their throwing items, so don't be surprised if you get nailed by a shell or bomb when no one is near you. There's a good chance you won't three star a cup on your first try, so just keep trying. Be patient and you'll eventually earn those bragging rights.