Well, might as well vote then ;p
Bracket #17: Landorus vs. Keldeo
Ehh, there's not really any contest here. I mean, while I reckon Landorus may be a cool Pokemon to use in battle and all, and even though I actually do like its backstory along with the requirements for catching it, its design along with the fact that it's a fifth generation Pokemon kinda throws it down the list for me :( Don't get me wrong, it's not that I don't like fifth generation Pokemon, it's just that I've never really got a chance to actually meet or battle with/against a whole lot of the fifth gen Pokemon due to never owning anything other than Black 2, which I haven't really played that much either D: But yeah, I kinda dislike all the designs from the trio, because I feel like they could've still gotten great Pokemon without having to make them super ugly.
But yeah, main reason there's definitely not contest, is because it's one of the few generation 5 legendaries that I've actually used, albeit not very much, but I still got to use it :p Also, all the times I had to watch through the Keldeo movie kinda gave me a soft spot for, and I mean. It's voiced by freaking Vic Mignogna, how much better does it get ;)
Bracket #18: Thundurus vs. Rayquaza
...I don't think I really need to explain much here. While Thundurus is actually my favourite of the three, partly because I prefer its design over the other two, simply because the light blue colour actually fits the design, and because blue and black don't look absolutely insane together, but also partly because I got to use in Pokemon Online when I used to play that, but I kinda fell out of that rather quickly :p
Either way, there's no question that Rayquaza would get the winning spot between these two, just considering the edge it gets on so many other Pokemon entirely because of its design. I mean, it has an awesome design, it's awesome in battle, and it gets a kinda awesome cut scene in R/S/E, and it's generally just overall pretty darn awesome :p Plus it has one of the coolest shiny sprites ever, so yeah. No contest ;)
Bracket #19: Palkia vs. Latios
another one that's mainly design-based. I mean, c'mon, are there anyone who actually finds Palkia's design to be somewhat pretty? I mean, it's not that it's a bad design, I've just for some reason never liked Palkia's design. I've also never liked purple, and considering that's one of the primary colours in Palkia's design, it isn't really doing well for Palkia. But yeah, the only fourth generation game I've ever played was Diamond, so perhaps I'm just kinda biased. In any case, Palkia's still a pretty good Pokemon???
But yeah, Latios definitely takes the cake here, just for the fact that it's a Pokemon I've actually been involved with in some way. I may never have caught Latios, but boy did I hunt for it. After realising that the off-looking Pokemon which I encountered near the Sky Pillar and had never seen before was in fact Latios, I instantly went out to try and catch it. After failing in my mission to catch the legendary beasts, I wasn't about to give up on one simple legendaryy. But alas, my hunts never came to fruition, and once I lost my game, I realised that there was no chance that I could catch. It simply wasn't meant to be ;'( DARN YOU LATIOOOOOOOOOOOOS! Love your movie btw!
Bracket #20: Kyogre vs. Mew
Seems as though these has all been votes without question. While I actually do like Kyogre as opposed to most of the other losing Pokemon in the other 3 votes, Mew has just lead to too many experiences and is too cute to not win. I mean look at that adorable thing! If anyone didn't d'aww at the windmill scene from the first movie, I'm convinced they're a cyborg. Anyways, after my experiences with trying to catch Mew in my original Blue, along with my search for it through all the rumours I'd heard about with other games, I've just kinda bonded with it much more than I have with Kyogre. I mean, Kyogre might have saved me during my playthrough of Sapphire, but that is the one time I've ever used it, and I honestly prefer Groudon over Kyogre anyways, so yeah. No doubt here :p