There are several ways you could go about unlocking this trophy.
Obviously the absolute quickest way would be to find someone who also needs the trophy or someone who's prepared to help you out and play one of the various 1 second versus levels over and over until you get your 25 wins.
Another way you could go about it is by simply playing the game the way it was meant to be played and try to get your wins legit against randoms - seriously though, good luck with that!
I came up with a method that sort of combines the two together. It's not the quickest way, but if you don't have anyone that can help you or you still want to get the trophy "semi legit" then here's what I suggest:
First, you'll want to make sure you've got your settings set to "always ask" for allowing people (randoms) to join you.
Then, go to the Community section and text search "Etienne". This should bring up a stack of 1 second levels where the host always wins.
Visit his planet and have one of these levels ready to load.
Now, just sit there and wait until you get a message "Such and such wants to join you...". Now you'll want to hit
so that they can join you and then as soon as you've done that start loading the level straight away.
This should time it nicely that the person will enter your pod and you'll pretty much immediately load into the level before they get a chance to see what exactly you're loading (they'll leave if they realise what you're doing).
Now you'll spawn in and immediately be at the scoreboard with a win. Keep hitting "Replay" as many times as you can before your "victim" finally gets fed up and leaves. If you're lucky you might get 5 or 6 done with the same person before they leave.
Rinse and repeat the process until you get to 25 and the trophy unlocks! Doing this took me about an hour and a half. Waiting for people to join is the time consuming part, but just do something else while you sit there and wait and you should be able to get it done in a reasonable amount of time. Hope this helps you get this somewhat annoying trophy out of the way