Sadly, but luckily finding a random online player is nonexistent, but you can easily unlock this achievement by double-boxing! I believe you need to be level 6 to be able to access rank so you can host a few Online Hosted games and kill your alt to level up (Same with your alt killing you) so you can reach level 6 faster.
Ranked Setup
Go to Online > Quick Play
Then Uncheck all boxes except 1v1 Ranked > Search
Do the same with your alt and it'll take a few seconds to match up with your alt.
Alternating between leveling up your main profile and your alt will be helpful so you can pair (even though you will most likely not run into anyone else, but just in case!)
You don't need to win, but as soon as the match is over, the achievement should unlock!