Howdy Honzo! I actually feel Viper’s match up against Ammaterasu is one of her better ones against the exceptionally good characters in the game. It really depends on your goal, in close you have scarier mix up that always leads into a dead dog if you don’t make mistakes, Ammy’s health is low so even starting a combo air to air you can kill her instead of normal situations where you need to start from the ground. Since I play both characters despite trying to go away from Ammy for Dante now I can give you some perspective from both sides.
Ammaterasu’s weird hit box is actually good for Viper, she’s fat enough that seismos ruin her life, I actually think lame viper is better than rush down viper in this match by a significant margin since on block or hit the hammer is very dangerous to the dog, and on whiff it can be made safe anyways. Make sure Ammy is in block stun if you’re getting point blank, her instant overhead/low game with an assist is very scary and just like anyone else when Viper’s forced to guess it’s bad for her. However you can counteract this by burning gauge on EX seismic hammer Beats every option the dog has except random level 3, and can be canceled into emergency combination if she does that Always make sure you have gauge if she’s rushing you down, blocking a good offensive dog is hard and should be avoided.
At mid range be aware that her normals are all safer than yours, either put her in block stun via seismo, use an assist to set up an advantage, or just be incredibly cautious as the seductive reach of 2B isn’t worth the fact that if you don’t cancel it you die for free to anything/everything. I honestly feel that the dog is at least 7/3 in Viper’s favor if she just plays lame which I have yet to do correctly.
Notes: Green reflector absorbs seismic hammer and neither party gain any gauge when it’s out, however Viper can punish when in mid range with a light/medium thunder knuckle cancel that leads into a dead dog assuming you had 1 gauge or good execution for post hit feints.
Ammaterasu’s air dash is horrible against Viper and should be avoided, it’s really easy to seismic hammer on reaction and block or hit that’s bad for the dog.
If the dog has the life lead she can run and be lame with superior super jump air normals. If the dog knows how to safely utilize the 236A in the air to just ware down the clock it can be obnoxious as super jump B, C, air throw, and S are all difficult to time correctly to beat out Ammy’s mash C with reflector. However if you can bait it doing CS EX burn kick as air to air leads into a dead dog thanks to the low health.
Never try to out prioritize her normals, it’s stupid and won’t work. I try this all the time assuming that I can anti air her with a normal, or meet her on the ground with something, hammer is fine for this, normals are not, she will win if you try to rely on the wrong tools, but every point in the match near the ground Viper has an advantage.
You can punish elemental super with emergency combination depending on the height, air throw depending on the distance, and EC/DHC pretty much always. Depending on your team mates killing the dog is normally a good idea as it can do exceptionally well against characters that aren’t Viper and I advocate burning gauge to get rid of it.
Also, what made you decide to try her out Honzo? I’m pretty sure if you got down seismo zoning with her our matches would be a problem as seismic zoning destroys Dog and Task so until I get a real Dante who has a relatively even match up against her it would be a huge problem if I lost Viper X_X. With your zoning prowess I forsee this becoming an issue. >.<
Edit: As someone else said air dash = free seismo.However I disagree with them about Burst time. Do not use it against her outside of combos/punishing elements. As we all know Ammy can block while air dashing and good ones won’t just mash C every time no matter how aluring it is.
As for the match from the other side, Vipers like myself make the bad decision to press buttons that aren’t seismo and thinking they’ll win for some stupid reason, unless Viper is rushing someone down and has support/ the enemy in a situation where their fastest normal won’t come out, Viper will get hit out of pretty much everything. Luckily she can create these situations easily. If you want help as or against Viper just talk to me and I’m glad to help!