Yeah, the Ultra Beasts. I wasn't trying to get at them, since they're included in the Pokédex anyway so they're still accepted for lists. I suppose Ultra Beasts can be a Bonus Round too. I haven't included them in the image list I've made though.
Faded Pokémon that are behind another means they are equal to that position. My old list had Scizor as my 4th Gen 2 Pokémon, but I remember that spot taking a while to decide on. After rethinking, I prefer Suicune because the design is better, with the wavy mane and tails. The summon in Smash Bros is cool too. Do like Entei for similar reasons, but Suicune's colour scheme is better there too.
Kalos, Alola and Mega are purely based on appearance too, as I haven't got any games that feature these Pokémon. Unless I count Smash 3DS for the small amount that are on there. There were a few contenders for 4th on Alola, Tsareena, Golisopod and Litten. Everything else is a bit...eh to bad. Zeraora's a recent new Pokémon, and I thought the design is the most interesting in quite a while, since my favourites of Unova. Simipour is still my top favourite Pokémon for the animation it had in Black & White and closed eyes that instantly reminded me of Gin Ichimaru back then. Also for the moves it learns.
For Megas, top three were instant choices really. Charizard X's dark skin and blue flames look awesome, Mega Pidgeot looks majestic and Audino continues looking cute. Last one was a toss up with Banette, Mewtwo Y, Blaziken and Rayquaza's. The rest don't look that great to me apart from the odd ones that don't quite reach these ones. Ampharos wins mainly for the Dragon typing, and that it's Amphy, a favourite of Gen 2. Even though I've only gotten a Flaaffy so far in a Pokémon game.
Also my choices tend to go by how much I already like them, and how badass or cute they look. So...
Badass: Mewtwo, Gengar, Charizard, Arcanine, Suicune, Zangoose, Aggron, Luxray, Rampardos, Staraptor, Simipour, Snivy/Serperior, Braivary, Yveltal, Pangoro, Zeraora, Lycanroc, Charizard X and Mega Pidgeot.
Cute: Vulpix, Flaaffy/Ampharos, Misdreavus, Totodile, Milotic, Flygon, Lumineon, Lilligant, Snivy, Aurorus, Sylveon, Ribombee, Primarina, Mega Audino, Mega Ampharos.
Best Ultra Beast: Pheromosa. Only decent looking one, but even that is a stretch.