This is taken from my own solution for the Xbox 360 version of the game.
### Note ###
If you notice any differences with this version of the game due to a slightly different input delay between the versions, and this cause the execution of a combo to be slightly different, please let me know in the comments below.
The purpose behind me writing this guide is to essentially share some little hints and tips I learned along the way to getting the achievement and to also share the sources of information I used to help me get through each mission.
So firstly, here are a couple of links:
VesperArcades UMVC3 videos:
This has a link to a video for each character, showing all 10 missions being completed, and you can also hear and see the timing of his button presses which helps tremendously. I use a controller, not a stick and it still helped me. So it will definitely help you.
Mission mode discussion/help/tips etc http://www.xbox360achievements.org/forum/showthread.php?t=34...
This is a thread full of helpful hints and tips that people have shared whilst going for the achievement etc (even i've contributed a couple of little tips). The OP doesn't seem to have continued to keep the first posts up to date with all the additional info, but if you can't find tips for the missions you're after in his first posts, just use ctrl+f and check all 3 pages with that. There's A LOT of information in that thread, and believe me I wouldn't have gotten this achievement without it.
Ok now i'll just go over a couple of tricks that are essential to completing some missions:
Tiger Knee cancelling
Essentially this is where you cancel a move with a jump, so that you can perform it quicker. So for example, you want to do viewtiful joe's " Air Desperado" hyper, which is "D, D+F, F + ATK ATK" while in the air. But, you want to do it on a grounded opponent. This means you want to do it as close to the ground as possible. The way to do this is by performing the tiger knee technique. All this means is instead of ending the stick motion at F, you follow through to U+F. Basically you're buffering the hadouken motion into a jump, then the split second you see Joe leave the ground you hit 2 attack buttons and the hyper connects. This technique is vital in many missions as a means to OTG with Spencer and Phoenix etc. There are some cases when you want to use the Tiger Knee technique to cancel a launcher into a move, in this case you want to perform the tiger knee motion but at the same time perform the move before the character leaves the floor (examples of this being Strider mission 8 and Magneto Mission 10).
Using X Factor to your advantage.
Some missions are rather difficult, however can be made easier by completing it with X Factor activated as it increases the window you have to perform the combos. Dr Strange #7 has a really tight link towards the end. I was trying it for well over 10 minutes, then suddenly realised I could just use X Factor, did, and completed the mission first try. Strider #9 only took me 5 minutes because I completed it with X Factor active. I feel Deadpool #10 and Iron Fist #10 would have been impossible for me without the use of X Factor also.
Don't mash buttons.
I know this might sound redundant, but it's an easy habit to get into, and I was doing it a lot more than i realised as it kinda gave me a buffer for some of the timings, but it hurts a lot more than it helps on later missions. For example in Iron Man #10 after the air dash -> air M -> air H, you have to land and launch with S. I think I completed the mission 3 times but broke the combo because the animation for an air S started just before I hit the ground. Essentially, I was starting an air S and cancelling it into a standing S without realising because as soon as I landed the air H I started mashing the A button.
Finally, just as a rough guide, here's an image of the missions I completed when I hit 480. This is just a little guideline for missions that might be worth avoiding. However it's worth remembering that different people are good and crap at different things. I for example am crap at jump loops, which is why I haven't done Akuma #10, Wolverine #10 took me over 3 hours, and I only did Felicia #10 with the X Factor trick. Other people might find them easy but suck at combos with random dashes in. My point is, it's advisable to try and play to your strengths. Also, don't be intimidated by a mission objective and give up on it before you've really tried. Ammy #10 for example has the same move I think 6 times in a row, and the combo in general just looks a lot more complex than it is. Infact I think I completed that combo before i'd hit the 400 missions complete mark.http://imgur.com/UDIz77G
So yeah, please leave comments/feedback. A thumbs up would also be nice, and if you fancy giving me a thumbs down, please explain why so I can improve my guide.