I suppose since it is getting a lot of love here this will count as an unpopular opinion...
Pokémon Battle Revolution is, by a long shot, the worst Pokémon Game ever made.
It's not even about it not being a 'true sequel' or whatever to the Shadow Pokémon games. Even though Colosseum is my favourite game in the series (I unfortunately have not been able to play XD due to it's atrocious prices on the secondary market; a fate it shares with Ike's two Fire Emblem games), to judge PBR on that merit or to want it as a true sequel or what have you would be unfair as despite being on a home console and being made by the same company, that's not what it sets out to do.
Instead, I'll judge it by it's own qualities or complete lack thereof. As noted above, PBR iis a very, very, very lazy game. Let's go over the good qualities first - it did introduce Trainer Customization years before XY would do it properly, it did let you see your entire team in 3D and due to the different backgrounds, animations and the aforementioned Trainer Customization; it did look much nicer than DP's wi-fi. The game also gave you access to items, Surfing Pikachu, as well as Magmortar and Electivire which are notable because DP's way of obtaining them is one of the most asinine ways a Pokémon game could let you get one of it's brand new Pokémon.
If you managed to read that there should be a little problem if you look hard enough. These are all nice qualities; all nice little details... but they're just that. Details. Every good thing about this game is not from a gameplay standpoint, not from a story standpoint; not from any standpoint other than Details and possibly music (Mysterial or whatever he's called does have a kickass theme). Trainer Customization is cool but it's hardly a massive selling point. Wi-Fi already existed in the DS games so it's not exactly a major draw. Aside from that it... looks nice? And if you're buying the game for a Surfing Pikachu and easier access to certain items it's at that point you have to step back and realize "holy shit, I'm into Pokémon way too deep".
So what's so wrong with the gameplay? If those are the only good things about the game then what's so bad about this game's gameplay that you can't list a good thing about it? ... the fact that, as I've noted before, there is no gameplay. When you sell a game for full retail price alongside titles like Super Mario Galaxy, Legend of Zelda: Twilight Princess, Super Smash Brothers Brawl and Metroid Prime 3: Corruption, that is a very serious problem. "But Kurona!" I hear you yell. "It does have gameplay! The Colosseum Mode!" ... if I were to count that as 'gameplay', I would seriously have to lower my standards. A long, tedious amount of battles in a row, with no break, with no overworld exploration, with no actual adventure or semblance of a story in-between which, if you don't connect your own copy of DP you get handed a choice of two teams of shitty mid-evolutions is what we call 'gameplay'? If Game Freak were to take Pokémon Emerald, strip the game of everything but the Battle Frontier and hand you a tenth of the Pokédex for you to choose your team from, it would have a tremendous amount of gameplay more than this full-retail price Nintendo Wii game. The Colosseum Mode exists purely for you to get Poké Coupons to spend on items. If you somehow got any enjoyment out of it, I commend you, because I certainly don't have any fond memories of it aside from Mysterio or whoever's theme.
And it's not even that that gets to me. It's the lack of value that does. I said I wouldn't judge it by the merit of Colosseum or XD, but you know what? Say you're a kid who loves Pokémon but for some reason you only have a Gamecube and no GBA. Guess what? There's these two great Pokémon games for the Gamecube on sale which give you a wide, if limited amount of Pokémon to choose from with their own unique stories, characters and overworld! If you have a GBA and RSEFRLG, then even better because you can transfer Pokémon to and from! Know what had less playability than that? Pokémon Stadium 1 and 2. But you know what? At least with those, you had fun minigames, Random Battles to play against your friend, and hell, I'll even give the mini Battle Frontier a pass here because those didn't exist in the Gameboy games and it featured characters people knew and love from said Gameboy games.
But Pokémon Battle Revolution? Guess what kids, if you want anything out of this; fucking anything, you have to buy an entirely different console and one of the DS Pokémon games if you don't have one already! Oh, and make sure to complete those first because you sure as hell are not going to be able to do a damn thing with your level 20 Luxio and Grotle. And I don't know if this was an unfortunate thing of where I was, but Battle Revolution cost MORE than your average Wii Game! When it was sold in the same shop in the pre-owned section; the section where everything's cheaper because it's pre-owned and hence was the cheapest place to get it... it cost the same price as a normal Wii game. That's my problem here. Not only does it offer no content on it's own for the price of a normal game, but if you want anything out of it, you actually have to buy a DS and a DS Pokémon Game. It's absolutely atrocious, money-grabbing and despicable. It's an accessory at best touted as being as valuable as classics like Super Mario Galaxy when really, even fucking Pokémon Ranch has more value - that at least has the decency to go under the radar, be sold for a very low price, market itself as an accessory, and give you a goddamned Mew. What does Battle Revolution give you? Oh, here's an Electivire, but hunt for a fucking code online first which we give you no direction to do.
There's nothing to be gotten out of Battle Revolution. It's not what one can call a game, not what one can call value for money and not what one can call fair in any way. It's just a shitty simulator.