Rocket League

You will need to start a party from the Main Menu by pressing . In order to unlock this you will need a second person; I cannot confirm if this can be done with a splitscreen account or not yet. According to Itzz Sh0wt1m3:
Once you have a person in your party, you need to highlight their Gamertag and press Invite To Trade. Trade any items you like and once the trade is complete you will get the achievement. Easiest one in the update to unlock provided you have someone you can do this with.

I should mention that you are required to trade and receive an item. You can't do either/or as far as I'm aware.

EDITS:

According to NoHeroes94, after extensive testing he speculates that item quality may be a factor for the achievement. Personally, I traded an Uncommon for an Uncommon and my partner and I both got the achievement, so you may want to anticipate that.

This seems to imply that unbalanced trades (in his case, an Import for an Uncommon) might not work for everyone. The person trading the highest quality gets the achievement in this case. It also implies that trading something back will not work, so a boosting party couldn't pass an item around the group to get the achievement.

This is all speculation though, and as far as we know it could be a bug. Just to be safe, you might have to trade a few times to get the achievement, and if you do you should try trading different things each time.

You will need one other person over online to do this (both will get the achievement)

-Start a party by pressing at the home menu
-Select who you would like to invite
-Once they've joined head to the bottom of the screen to where their name is displayed and press
-Then scroll down to 'Invite to trade' press again
-Once the trade menu has opened, select an item to trade them and wait for their offer (you both need to trade something)
-Press to accept the trade once you are in agreement, then hit okay on the pop-up text

As the other guides are a few years, old, I wanted to provide a more current guide since the game went free-to-play and Epic-integrated, it's now much harder to simply do with any 2 users, whether a friend, booster, or another user in your home if you have two consoles.

The requirements to trade between 2 people are as follows:

1. Both Xbox gamertags need to be assigned to an Epic Games account and accepted the EULA.

2. Both Epic Games accounts must be email-verified and have two-factor authentication enabled.

3. If a gamertag/account was created or new to Rocket League after the F2P transition, it needs to have purchased at least 500 credits (approx. $5USD/$7CAD).

4. Both accounts must be XP level 30 or higher.

5. All involved items must have been acquired on Xbox to be traded on Xbox.

It will not tell you this criteria all at once, if you attempt to trade without the above done, it will give you an error message first about the user agreement, and once that is done you'll get a message about 2FA, once that's done then about the credit limitation, then about the level requirement.

While you are apparently supposed to be able to trade items acquired from crates prior to the blueprint system, on my account around 99% of everything I had from the prior 3-4 years of crates is marked as not tradeable.

Swap Meet achievement changed to 'New Profile Who This?' to fix the previous achievement from being discontinued and this happened today (June 5th) when the previous season (14) ended (hence why they said this fix will be part of the Season 15 update) which came out yesterday (June 4th)

Basically the new requirements to get this achievement will be to change your profile banner, border and a player title.

You get a banner while completing the beginner tasks if you're a new player or you already have a lot of them if you've bought the game previously.

The only one you might have a problem to get is getting a border. The best way to get them right now is to get luck and get them from a tournament drop (you can only play tournaments if you're level 20 and if you have a rank), level up to level 25, getting them from the free rocket pass (if one border is included on the item set), buying the rocket pass (which I don't recommend wasting 10 dollars on it) or get them through RLCS Fan Rewards stream drops. (the current item set for the fan rewards don't contain any borders/player titles/banners, but the old one did contain them all).

To get a player title the best way is to level up to level 20 or get them earlier from the free rocket pass item set (most of the rocket passes always contain one or two player titles very early so this isn't too hard at all)

In the past, you could've also gotten a banner and a player title through free codes, these 4 codes used to give player banners: 'RocketLeagueLive', 'wrestlemania', 'WWE18', 'wwedads' and this one code 'couchpotato' used to give a title. I'll keep this solution updated when more codes get available.

Now that you've got them all, head over to 'Profile' on the main menu, then, click to change the profile banner, choose a title and then a click and the achievement will be yours.

**NOTICE**
This achievement now requires you to have spent at least 500 credits or for you to have bought the game before it went free to play in order to complete.
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This achievement will require yourself and a partner over Xbox Live (Splitscreen will not work)

1. Launch the game to the main menu and start a party using then invite your partner to the party.
2. Once they join you, select their name and press to bring up a menu, then select "Invite to Trade"
3. Once they accept your invite to trade a trade menu will appear, select the item(s) you are going to trade them, and make sure they trade something back.
4. Once you are both satisfied with the trade, press and then select okay.

Boom Achievement Unlocked!