CAPCOM VS SNK 2 / Capcom / Dreamcast
There's an amateur game out there called MUGEN that is basically an open-source fighting engine. It allows you to download characters that people have made and throw them all together into one giant roster, and pretty much every fighting game character from every commercial game at this point has been given an accurate representation by someone. While people do great jobs getting the moves, look and feel of these characters down, a MUGEN brawl never seems quite as "on" or satisfying as a good release from a major publisher like Capcom or SNK, chiefly because "balance" is a really tricky thing in a fighting game and takes a professional, experienced touch.
Capcom vs SNK 2 tosses 44 fighters into the pot, 22 from each company's stable, and what's worse they seem to have ripped the sprites directly from a multitude of games ranging from the then-recent Street Fighter 3 and Garou: Mark Of The Wolves to comparatively ancient sprites from Super Street Fighter 2 and the original Darkstalkers. Yet, somehow, in some way, this all works out. The game plays a bit more like the Capcom side of things than the SNK side (likely given they did the majority of the development on it), yet the SNK characters "feel" right and it doesn't really feel like you're compromising their play style to be effective with them.
All 44 characters are available to you at the outset of the game, so you don't have to fiddle about with endless point-scoring as in Marvel vs Capcom 2. If you dig unlocking stuff, though, you'll still be racking up points to spend on the Groove system. There's six pre-set Grooves you can choose from at the outset of each battle, which basically determine your bonus battle abilities (whether you can roll, evade and parry for example) and how your Special meter fills. Each of the six Grooves are based around the ability set and special meter from a particular game or series - the C groove is Street Fighter Alpha 1 and 2, A is Alpha 3, P is Street Fighter 3, S and N are KOF's Extra and Advanced modes, and K is Samurai Shodown. What this essentially means is that characters from one game can play like a character from another - Ryu can get the rolling evades and short jumps of the King of Fighters stable, Terry Bogard can parry like the best of them in Street Fighter 3, etc. You'd think that between the random sampling of characters and this, the game would be a broken chaotic mess, but somehow the experienced pros behind this sorted it all out so that it works smoothly and there's very few overpowered/irrelevant characters or settings. The best aspect is that there's two "EX" slots in which you create your own custom groove by purchasing abilities and a super meter type with the points you win playing the game solo. In time, theoretically, you could add nearly every ability from every game with a custom super meter of your choosing.
For further customization the game employs a "ratio" system which allows you to do either traditionalist one-on-one Street Fighter matches, KOF's three-on-three, or somewhere in between. You can force either one-on-one or three-on-three, but in Ratio mode, you are able to select up to four people but can opt to have as few as one. The less you have, the more of a strength bonus they get.
To deal with the issue of button configuration, the game uses the six-button style of Street Fighter. Most of the SNK roster comes from KOF, plus has their own series of multiple games to boot, so their "extra" two moves are added in usually by sort of taking a sample of moves from different games.
As mentioned before, the one mis-step here is not re-drawing all the sprites for the game, or at the very least bringing the old sprites up to the level of SF3 and Garou. It's only a small handful of characters that look really bad (Morrigan, Cammy, E. Honda) but when they do appear they look glaringly out of place. They play fine, they just look weird. I also could have done without the "blade" characters from Samurai Shodown and Last Blade. I can deal with swords in something over-the-top like the Marvel VS series but this game is a little too traditionalist and they seem really out of place.
I would say CvSNK 2 is a bit more to the "hardcore" side simply due to a lot of the appeal being in fiddling about with Grooves and making these old characters do all sorts of new things. But it's certainly balanced, playable and welcoming enough for a newcomer to enjoy it too, though they might be put off by the lack of story and unlockables.
* Gameplay Video