I've noticed that SSB has addressed and corrected the problems of its predecessor. Here are some of the problems with:
Melee
-6 clones out of 25 characters. 1 was a semi clone, making it 6.5. In total, 12/25 fighters have extreme similarities.
-Most characters can't return to the stage due to their UpB. The 8 that are guaranteed are Fox, Pikachu, Zelda (not Shiek), Kirby, Jigglypuff, Peach and DK in some cases.
-Kirby's throws can be broken out of (in mid animation) due to lack of hands.
-A lack of stages make some characters essentially homeless, and other stages are used to fill the role. Ganon (Brinstar Depths), Roy (Final Destination), Young Link (Jungle Japes despite Great Bay being his stage), Bowser (Rainbow Cruise), Dr. Mario (Kingdom 2), Mewtwo (Battlefield), Link (Great Bay on All Star) and Pichu (Four Side) are examples.
-Bodies of water have no effects on fighters. This makes Jungle Japes and Great Bay seem strange because the fighters float like bricks in the water.
-CPU opponents can't detect motion sensor bombs, and stay in place (horizontally) when using a Warp Star.
I can keep going but I'll stop here. You'll notice that many of these problems were corrected in Brawl, and despite that, the 3rd game has problems of its own. I'm confident that SSB4 will correct Brawl's dilemmas. Can you guys add to this as well as a list for Brawl? I'll start on SSBB's flaws eventually.