I'll try to answer this the best I can...
King Dedede
In truth I've originally mained Kirby since the original Smash 64.
I was a huge fan (and still am) of the Kirby series since I was a kid. Kirby was a main that stuck with me through out all of the Smash games; however I didn't start ACTUALLY learning things till Smash U despite my countless years of playing Smash.
To be honest, I don't really know how or why I exchanged Kirby for King Dedede despite staying with him for so long. Even more baffling I absolutely despised King Dedede in Brawl. I hated how he played and he was one of those characters I did awful with. For some reason though I began to like him in Smash U and he began to stick with me. Eventually I was playing him non-stop and began to enjoy him a ton. Perhaps it was his Bait and Punish nature, or maybe it was the range his hammer gave him.
Either way, I do regret phasing out of Kirby for King Dedede but at the same time don't regret learning him at all.
ROB
This one is a lot easier. I'm a retro nerd, plain and simple.
I loved Mr. Game & Watch in Melee and Brawl, and I loved ROB to death in Brawl as well. In fact, I even flipped out when Pac-Man and Duck Hunt were revealed. I was even DESPERATE to main Duck Hunt. Sadly I was just an absolute terrible Duck Hunt, and same goes for being really bad at Pac-Man; however ROB has stuck with me since his Brawl reveal and I love him.
I sadly phased out of Mr. Game & Watch though, but still use him from time to time. He just doesn't feel the same.
Bayonetta
In truth, I have always been seeking out at least one Top Tier character I can use.
None of the Top Tiers I really liked or didn't sit well with me. A lot of them were just... Really uninteresting to me, but then Bayonetta happened. I was also determined to main her when she was revealed and released but ended up dropping her at some point due to the massive Witch Hunt she received. I couldn't take the hate anymore that she received on For Glory. Having everyone ragequit, insult you, copy you, and just get plain salty over and over did not make the game fun for me at all. It was annoying.
After her massive nerf though, I decided to pick her up again. Even better, she got ranked as Top Tier.
The thing that I love most about her is her air combo game. I tend to love the air-style fighters the most and she just feels perfect to me. Of course I still get people who ragequit or spill the salt when I use her but I've learned to stop caring since then. I've been pouring my heart and soul into learning her and how to be a great Bayonetta player. Her cheekiness is also a bonus.
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Aside from these facts, there's also some similarities these three tend to share:
- Each one has AT LEAST one projectile they can use
- All of them have pretty great recoveries (in terms of being able to recover from almost anywhere)
- Each has average run speed at best
... Just to name a few. Also sorry for the long post. You're a trooper if you read through all of this!