Hooray! A fighting game that doesn't come with a large number after it! To celebrate this momentous occasion, let's break down design choices made here that are deliberate, progressive moves that could not have been made to an existing Capcom IP. For obvious reasons, we'll be comparing this game directly to the Marvel vs Capcom series.
Controls In general, Capcom fighters have a 6-button layout:
Jab (light punch)
Strong (medium punch)
Fierce (strong punch)
Short (light kick)
Forward (medium kick)
Roundhouse (strong kick)
This was fine in the arcade, but the home consoles had some issues with control. The Sega controllers and the Xbox Duke controller were able to handle the 6-button layout relatively well, but most people got accustomed to the light and medium punches on the 4 face buttons, and the power attacks on the triggers.
Tatsunoko vs Capcom changes this layout quite a bit:
A (light attack)
B (medium attack)
C (strong attack)
Not only does this make the game far less intimidating to newer players simply by reducing the quantity of buttons, it cleans up the button layout so that all the necessary buttons are available and easy to find on a traditional 4-face button game controller.
Ironic, then, that this game is a Wii-exclusive.
Combos Every character in Tatsunoko vs Capcom can launch his opponent with the same control (d/f+C), much like the d/f+2 uppercut from Tekken. Combined with the easily accessible tech crouch low attacks (d+C or even d+B), this choice allows players to at least use the basic tools of the game with every character available, forcing mix-ups and chaining combos.
Essentially, the game is broken down to the point that any attack on hit will grant a free attack of a stronger group (this is a simplification):
Jabs will guarantee a buffered Strong
Strong will guarantee a Roundhouse
Roundhouse, a Special
Specials will cancel into Supers
Supers can be used to start Delayed Hyper Combos
This means that, first of all, chaining combos in this game isn't really all that difficult. Pressing A, then B, then C is not hard. It also means that basic combos (A, B, C, qcf+C, qcf+A+B) can basically work for any character, netting them around 50% health. In other games, learning half-life combos takes a while, especially with different characters, but Tatsunoko vs Capcom encourages experimentation by lowering the barrier of entry.
Supers Many changes made to the use of the Super meter are essentially lifted straight from the Guilty Gear series, games that were once lauded for introducing fresh, progressive ideas into a stifling, tradition-centric genre.
The Super bar was always used to use Super attacks, but now can be used to defend against them. Similar to Guilty Gear's Faultless Defense, Tatsunoko vs Capcom's Advance Guard will eat a bit of super to completely avoid chip damage.
The Super bar can also be used for Baroque Cancels, which completely negate recovery frames, similarly to Romantic Cancels from Guilty Gear. Not only will this extend combos, it will trick opponents into attack after blocking a move that should be unsafe due to its recovery. The ability to combo ABC into A again with bonus damage isn't just broken, it's Baroquen.
Lastly, characters can Hyper Crush, which is a Burst from Guilty Gear. Hyper Crush is a get out of jail free card that players can use to stop guaranteed even combos and knock the opponent away. Since this game uses it with the Super meter and not on its own timer, Hyper Crush can be more easily rationed during a match, and it's more of a tactical decision to use it.
Fighting games in general are really hurting right now, mainly due to their esoteric rule sets that no one wants to bother learning. However, without this level of depth, they wouldn't be worth really playing in the first place. It's time for a compromise!
Controls Playability: Make it fit the damn controller Depth: Allow for multiple tiers of specials and supers Compromise: Set the same 3-level tiered system on a new 4-button layout
Combos Playability: Make them easy and awesome looking Depth: Create variety between characters so it's not essentially mirror matching Compromise: Create easy dial-in combos (DOA's PP6PK, VF's PPPK, TvC's ABC Special Super) that are worth decent damage, but also include character and situation specific combos for even more damage
Super Moves Playability: Again, easy and awesome Depth: Force players to perform difficult setups to reap the best rewards Compromise: Again, ABC-Special-Super. Also, the tiered Super Level system (level 1, 2, or 3, just like the attacks)
Tatsunoko vs Capcom is trying hard to find the right compromise, and it seems to be a step in the right direction. We'd see plenty of awesome gameplay modifications to this genre if it consisted of anything other than just sequels.