Scott Pilgrim vs. The World: The Game

It's all in the Reflexes; fastest and easiest method:
This can be done while going for Speed Run or whenever. During the movie set sequence in the second level (can't remember the boss' name) there is an area where the director hops in the middle of the screen and shouts some stuff. He abruptly absconds and you are left to fight some dinosaur/alien actors. Kill all but one and pick up a rock. Try not to hit the remaining bad guy, dash-throw your rock at either end of screen and hold B. That's it. Just throw the rock and hold B 25 times. As long as the screen in locked on a particular area the rock will ricochet between the sides of the screen until in loses momentum or you catch it (or hits you (which won't happen if you're holding 'B')). If you don't get it right then and there, there is a different scene a few second away. A bomb will appear from the ground and you have several seconds to 'break' it. Instead, take your pet rock and throw it at the side again. Took a whole 20 sec of game time. Hope this helps.

For this achievement, go into Battle Royale mode . You should have it. (its in the extra modes)
Then, you and another player go into it. Note: The second player must have an account.
You toss the thing from person to person. There are items on the sides of the arena, I found that the bucket and radish were the easiest, but that may just be me. Anyway, all characters should be able to catch just as Knives can. I used a friends account's level one Kim Pine, and that worked (just in case it isn't true for all characters). Just mash B button (catch) while you press Y (throw) with the other controller and vice versa 25 times (this takes a few minutes, but isn't really hard). Or if you have a friend, mash B button when they have it, use Y when you have it. Be prepared to get hit a few times.

Note: This is what I did and it worked fine.

The easiest way is to do this in Co-Op.

Player 2 throws the object, Player 1 (Chau) just catches it.
Throw the object back to player 2 then just rince and repeat this little game for another 24 times.

If you are alone. I actually did this, controlling both players myself. That's not too difficult.

Another quick way to do this other than those listed that can also be done in single player (it can be done with level 1 Knives on the first stage), is to play the first stage. Any time you see a blonde guy with a blue jacket, kill everything else on thee screen. Provided that there are items for him to pick up, the blonde guys with blue jackets will almost always approach them and throw them at you. Time your catches right and try to avoid killing the blonde guys with blue jackets, and you can get this achievement about 5-10 minutes into the game playing as Knives.

if u have two accounts just play a game of dodgeball with the second player and throw the ball back and forth. I'm pretty sure u'll earn item catch with knives around level 7-8 (sorry if i'm wrong)

(really!? who negative voted please explain why)