Rocket League

First solution is great if you have a group..if not, I was able to do this by myself. Albeit an annoyingly convoluted way. Followed the above solution as far as..private tourney, 2v2, best of 1 etc. Had my profile and girls signed in on home console. Then signed in random profile with guest on my other Xbox. Joined up tourney. Scored. Boom. Done. This is of course if you can't find anyone. Also I only had two controllers. Definitely annoying and tedious, but it'll get the job done! 😁

**Edit : vSully pointed out the prior solution I was referencing has be deleted. The Tournament set up is as follows:

Create Private Tournament
Team Size: 2 Vs. 2 (no need to be more)
Bracket Size: 8
Standard Match: Best of 1
Mutators: 1 Goal
Joinable By: Name/Password

Then Create Tournament..
Then On second Xbox...select join tournament..type in tourney name and password...join..register..good to go!

Feel free to Let me know if there is anything else I can or need to adjust. My apologies if the layout isn't done well. New to posting solutions, bear with me and I'll update accordingly 😁

This achievement is actually fairly simple, provided you have the requirements.

Needed are:
One friend who has two controllers.
Two controllers yourself.

First things first, launch the game with the controller/account you want to get the achievement with. On the other controller, sign in as a guest. Upon entering the game, press on the dummy account, and you’ll start a party with two people.
Tell your friend to do the same instructions as above so you have two parties.

On your account, select Play, Tournaments, then Create Tournament.
Give it a unique name, and make the team size 2v2. Select Mutators, and set the Max Score to 1 Goal. Leave that menu, then make the game Joinable By Name/Password. Finally, hit Create Tournament. You will get a menu where you set the password. Enter whatever you’d like. Finally, confirm the settings and the tournament will be created. Lastly, press to register, and enter a name if you’d like.

Now, your friend has to register for that tournament next.
They have to go to Play, Tournaments, and Join Private. Have them enter the name and password, then have them register by pressing upon selecting the tournament.

Now just wait for the timer to finish. A match will begin between the two teams.
Simply score a goal, and the match will finish. Because you scored a goal, you will be awarded MVP, thus getting you the achievement.

Thanks to the new tournament update added with f2p, you can now complete this achievement as a solo queue player.

You can now sign up for tournaments other than the ones set up by other players which allow for solo queueing into matchmade teams, they seemed to be available every few hours when I did this.

When you join a tournament you'll likely have to wait for it to start for a while. Once you're in a match you need to finish top of your team and win the match to get mvp, no requirement for winning the whole tournament. This shouldn't be too difficult for anybody as these new tournaments try to match people of the same skill level.

Sorry if the format for this guide is poor, just wanted people to be aware this update makes it easier for solo players.

This isn't a solid guide YET for how to obtain, but I do have these pointers I've learned for for those of us that only have one Xbox.

1. You cannot do this solo you must be partnered in a 2v2 tournament at least.
2. Setup tournaments yourself and in Requirements limit the highest level to your level. That way you are playing against people your level or lower. Otherwise you'll have a pro join and wipe you. (I'm Silver 1 in 2v2 and 3v3 currently and playing a Platinum would just be painful.)
3. You still have to not only win the game AND be the best player on the team, but if you get someone to partner up with you that is about your skill level you have good odds. OR if your buddy can try to setup shots for you by centering the ball for you to take the shot. If you happen to have the lead, your buddy can score so long as they don't out score/perform you.

Alternative method:
Either have 1 friend and both of you have a 2nd controller, OR get 3 friends together and setup a private tournament and then you can see who is best for the first round and then next round help whoever still needs the achievement.

Hope these tips are helpful. Still working on this one myself....and now I started reading through the comments on the other solution and saw a lot of what I posted above. Still Going to leave it out here because not everyone reads through all the comments.