From Shoryuken Wiki, Marvel vs. Capcom 3 Strategy and More!
This guide section, and it's subpages, describe the Game Systems in Skullgirls. Knowing the details may give new Skullgirls players an understanding of how to improve their gameplay. Players with experience from other fighting games may want to understand the similarities and differences between Skullgirls and the fundamental gameplay in other fighters.
- Glossary: An index of move properties and a general fighting game vocabulary reference.
- Frame Rate, Timing, and Animation: Frames, Frame Skip, Start Up, Active, and Recovery Frames, Block Stun, Hit Stun
- Character States: Fill in the list of subjects
- Hit Boxes: Attack Boxes, Hurt Boxes, Physical Extent
- Commands and Inputs: Fill in the list of subjects
Character Ability Systems
- Movement: Walking, Dash and Run, Jumping, Air Dashes
- Basic Attacks: Normal Moves, Command Normals, Normal Throws, Special Moves
- Basic Defense: Blocking, Pushblock, Ground Recovery, Throw Tech
- Advanced Attacks: Ensembles, Tag Outs, Outtakes, Blockbusters, Stunt Doubles, Blockbuster Sequels
- Combo Mechanics: Notation, Chains, Cancels, Links, OTGs, Landers, Character Size and Weight
Defending characters get a brief period of unblockable protection after successfully blocking any attack that forces a specific block direction. This protection lasts for the duration of the attack's hit stop, lasting between 4 and 12f for most attacks. During this brief period all attacks requiring a change of block direction will get blocked automatically. The fearsome left/right and / unblockable setups, common to many 2D fighters, will not guarantee a successful hit as long as the defending player can block the first hit. At worst, these tactics will require the defending player to make a 50/50 guess.
|Cerebella guards high against Painwheel's j.MK, then automatically blocks Ms. Fourtune's c.HK custom Ensemble.|
The Infinite Prevention System
Hitting an opponent with an infinite combo allows the defending player to break out of the combo with a unique Infinite Escape attack. An infinite combo uses a repeated sequence of the same attacks and can deal 100% damage to the defending character. When the Infinite Prevention System (IPS) detects an infinite combo, hit sound effects and impact effects change and any attack input by the defending player will execute the Infinite Escape.
All characters have identical properties for their Infinite Escape: 10f of invincible start up, 23f active frames, and 28f of recovery. The Infinite Escape can start the frame after an IPS triggering attack lands. The defending character is invincible during the the entire Infinite Escape and can take any available action at the end of recovery frames as long as the Infinite Escape hits or is blocked. Under normal circumstances, both characters will recover on the same frame after a blocked Infinite Escape  If the defending player preforms an Infinite Escape after a projectile triggered If it does not hit, the recovery frames are vulnerable and there is an additional period of recovery as the character falls slowly to the ground and lands standing.
I'm not sure why people think this IPS is complicated [...] the rules are still simple to explain - "don't start a chain with something you already hit with, and your combo is always legit." You get 2 free sections before moves are even counted toward this limit (your first and second chains) and one more free section where moves are kept track of but the limit isn't enforced yet (the entirety of your jump if you're in the air, or your next chain if you aren't). That's it. You can determine exactly whether or not a combo is possible just by writing it out: "Did I already use s.LP? OK, can't start another chain with that." And if something doesn't work, the hitsparks change color and you immediately know which move caused it. You also immediately know why, because the ONLY THING that would cause it is you having used that move before. 
"Don't start a chain with something you've already hit with" is the only rule. The exception is your first jumpin sequence, first ground chain and first air combo. 
- IPS reads combos in as smaller sections, chains, or loops as they happen. It offers the most freedom to the attacking team during the first sections then becomes increasingly strict as the combo continues.
- Any attack will start a new section. The section continues through any chain combo of normals, a cancel into a special move, or a cancel into a Blockbuster.
- Leaving the ground with a jump, landing on the ground, air dash canceling, and preforming a link in a combo all start a new sections for the combo.
- The first air dash cancel in a combo will never increase the combo stage. It always starts a new section.
- Like air cash canceling, Painwheel's Flight will start a new section without increasing the combo stage once per combo.
- Blockbusters will never trigger IPS. Infinite Escapes can be preformed while getting hit by a Blockbuster if something else triggered IPS first.
- Ensembles count as their own section. IPS will remember an Ensemble attack if the Ensemble character becomes the point character before the end of the same combo.
- A , if used in a combo after a or stun, counts as its own section and cannot trigger IPS. Infinite Escapes can never be preformed during a throw's animation.
- A 1f reset between combos will not reset IPS.
- Some attacks have special rules for IPS:
The Practice Room's combo stage counter counts up from 0 to 5 for the attacking team during a combo, showing the player when IPS increases the restrictions for the combo. The IPS effecively ignores the combo for the first free sections. The IPS remembers all attacks used in a combo starting with the first watched section. After a combo reaches the maximum combo stage, the IPS continues to watch and remember every attack and can trigger for the Infinite Escape. Starting any additional section with a move that was previously used in a watched section will trigger IPS. 
- 1: Free: Optional section for a sequence of jump-in attacks.
- 2: Free: First ground section.
- 3: Watched: First air section or second ground section.
- 4: Watched: Optional special case section if opponent lands on their feet after stage 3.
- 5: Limited: Maximum stage, same as watched and can trigger an Infinite Escape.
Many IPS rules were first shown in this combo by Urichinan:
Unfortunately, some of Peacock's move properties have changed since this early version. This combo will not work in a release version of the game.
The complete combo can be written out as:
j.MK, j.HP xx air dash, j.MP, c.HP, s.HK xx ↓↘→ + LK, s.MP > s.HK xx ↓↘→ + LK, walk forward, (land) s.MP > s.HK xx ↓↘→ + LK, walk forward, s.LK (land) > s.MP > s.HK xx ↓↘→ + LK, walk forward, c.LK > s.MP > s.HK xx ↓↘→ + LK, walk forward, c.LP > s.MP (land) > s.HK xx ↓↘→ + LK, s.MK xx super jump, j.MP xx air dash, j.LP > j.MP, s.LP > s.LP > s.MP > s.HP xx ↓↘→ + MP (wall bounce), OTG c.MK > s.HP xx ↓↘→ + HK xx ↓↘→+PP
Breaking this up into what the IPS considers sections gives the following:
- j.MK > j.HP xx air dash, j.MP - Stage 1 section (jump in section), ignored by IPS, ending when the attacking character lands on the ground. The first air dash cancel in the combo does not start a new section, allowing Peacock to get 2 air chains in the free jump in stage.
- c.HP, s.HK xx ↓↘→ + LK - Stage 2 section (first ground section), also ignored by IPS. Linking after the qcf+LK starts a new section.
- s.MP > s.HK xx ↓↘→ + LK - Stage 3 section (second ground section), and the first watched by IPS. IPS watches s.MP, s.HK, and qcf+LK for the first time in the combo. Infinite Escape will not trigger in a watched section.
- (land) s.MP > s.HK xx ↓↘→ + LK - Stage 4 section (special case with opponent landing on feet), also watched by IPS. Using this special case allows Peacock to start a chain with s.MP one extra time. As an exact copy of the last section, this section quite conveniently doesn't limit any additional moves for the combo.
- s.LK (land) > s.MP > s.HK xx ↓↘→ + LK - Stage 5 section, and the first fully limited section where IPS can trigger an Infinite Burst. IPS watches s.LK for the first time.
- c.LK > s.MP > s.HK xx ↓↘→ + LK - IPS first watches c.LK. Starting a chain with a new move then using watched moves for the rest of the section allows Peacock to loop a sequence of watched moves.
- c.LP > s.MP (land) > s.HK xx ↓↘→ + LK - IPS first watches s.LK.
- s.MK xx super jump - IPS first watches s.MK. This single move section ends with the super jump cancel.
- j.MP xx air dash - IPS first watches j.MP. This single move section ends with the air dash cancel.
- j.LP > j.MP - IPS first watches j.LP.
- s.LP > s.LP > s.MP > s.HP xx ↓↘→ + MP (wall bounce) - IPS first watches s.LP and s.HP. All of Peacock's normal moves that chain into s.MP are now watched. The defending character goes through the wall bounce before hitting the ground for a normal knockdown.
- OTG c.MK > s.HP xx qcf+HK xx ↓↘→ + PP - IPS first watches c.MK. Hitting the opponent after the knockdown uses the one OTG for the combo.
Combo video champion Desk first attempted to explain IPS with this video:
The complete combo can be written as:
j.HK, s.MP (stagger), j.HK, s.MK > c.HP xx super jump, j.HP, s.LK > c.HP xx super jump, j.MK > j.HP, c.LP > c.HP xx super jump, j.MP > j.MK > j.HP, s.LP > c.HP xx super jump, j.LK > j.MP > j.MK, c.MP > c.HP xx super jump, j.LP > j.MP > j.HP, s.MP > c.HP xx →↓↘ + LP+LK xx ↓↘→ + PP, OTG c.MK > c.HP xx →↓↘+LP+LK xx ↓↘→ + PP
Breaking this up into what the IPS considers sections gives the following:
- j.HK - Stage 1
- s.MP (stagger) - Stage 2 (first ground section). Additional uses of s.MP will not stagger again in this combo.
- j.HK - Stage 3 (first air section)
- s.MK > c.HP xx super jump - Stage 5
- s.LK > c.HP xx super jump
- j.MK > j.HP
- c.LP > c.HP xxx super jump
- j.MP > j.MK > j.HP
- s.LP > c.HP xx super jump
- j.LK > j.MP > j.MK
- c.MP > c.HP xx super jump
- j.LP > j.MP > j.HP - IPS is now watching all 6 of Cerebella's air normals.
- s.MP > c.HP xx →↓↘ + LP+LK xx ↓↘→ + PP
- OTG c.MK > c.HP xx →↓↘+LP+LK xx ↓↘→ + PP