Sonic the Fighters

Since it's random for the CPU to use this attack on you the easiest way of getting this done is with a second controller.

Start up Offline Versus, pick any character with the controller getting the achievement, and then pick Amy with Second controller.

When the match starts just hit (Down + A button) on the Second Controller for an easy 40 Gamerscore.

A Small Transformation - 40G (Original Achievement)

Difficulty: 2/10

To get this Achievement, you must be attacked by a specific Hammer type attack that only Amy uses.

So you need to get to Stage 2 in Arcade mode and let Amy beat up on you until she uses it. I changed the Difficulty to "Hardest" and sat there until she used it, if she doesnt and you are defeated, you will get the chance to Continue and try again so do so.

Amy's correct attack will start with a short scene where she points behind you and then smashes you with her Hammer after you are distracted. The Achievement will unlock right after you are hit.

You can also get this in Offline Versus by having your 2nd Controller play as Amy and use the attack on you (Down + A). This may be quicker assuming you DO have a 2nd Controller.

For this achievement you'll need to be attacked by Amy's hammer down attack and be squished by it.

The best/easiest way to earn this achievement is to go into Offline mode and use a 2nd controller. Now Pick any character for yourself and choose Amy as the 2nd controller. And once the match starts walk upto your character with the 2nd controller and press Down + A.

If done correctly you'll have squished your character and popped this 40G achievement.

The following video will show you how to unlock the achievement.