For anyone wanting the arcade/singleplayer achievements/trophies easy:
Go into game options in the option menu.
Game time: 30
Damage Level: 1
For the theme teams:
Avengers: Ironman/Ironman/Ironman (Projectile)
Darkstalkers: BB Hood/BB/BB (Projectile)
Street: Ryu/Ryu/Ryu (or Ken/Ken/Ken, Akuma/Akuma/Akuma) [Projectile]
X-men: Cable/Cable/Cable :lol (...Projectile, again!)
For Avengers and X-men: Spam HP. (Ironman: Down+HP, Cable: HP) while spamming A1/A2.
For Darkstalkers/SF: Good luck, as there isn't a mashable attack for either (BB can Down+HP, but it isn't practical/abusable), basically get them to hyper/DHC a bitch to low health and time out for eight rounds.
You'll usually time out someone (unless you play Cable at damage level 4, in which case spam HP, A1/A2 and then dual-hyper-combo viper-beam a bitch).
Once you get to Abyss it's a matter of time outing him.
YES, you read that right. Abyss can be defeated with time-outs, provided you have MORE THAN ONE CHARACTER left. Build your super meter to level 5/MAX during the first two rounds (just don't lose anyone, just punch/punch/punch/block!) and then DHC the third one to low health. You'll either kill him with two DHC or have him low enough to just time-out.
Easy. I've done the singleplayer achievements in both console versions.