Override: Mech City Brawl

During an Online Match (And yes you can boost with friends by just inviting them to a battle)

You have to win on each of these maps at least once:

Japan (Required for the Watchbot achievement)
Egypt
Norway
Morocco
Lunar Base
Mexico
Russia
Bhutan
Brazil
United States

For most of of these online achievements, they can be done in a shared mech in team mode, and all the players in that mech will get progress towards these achievements.

So instead of needed to do each map for each player possibly 2 times, you'll only need to do each one a single time, if you're all in a shared mech. So just put all players in a shared mech, and add another mech on another team with another controller. The AI bots you can add might work as well, but I cannot currently confirm that.

I was able to get most of the specific mech attack achievements to work in a shared mech as well, so "Used MetaGeckon's rolling ability 30 times in online matches", or "As Vidar, trapped enemies 3 times in a single online match", etc. Even if only the main host player did the inputs the other person/people in the shared mech will unlock the achievements as well. The online attacks achievements that need an ultimate attack didn't seem to work though. We tried a few times with a couple of them, but they didn't unlock in a shared mech. Maybe we were doing them wrong, but I'm not sure.

Not sure a ton of people will be playing/boosting this game, but knowing this tip should cut down on online boosting time considerably.