More info about Party Time - 1st level in Campaign, when you need to break generator don't do it. Go back to your spawn (small blue box), jump, go right, go through big red box, go right.
For Gamebreaker, you need to put a Tesla Coil (Engineer's killstreak) in front of Jyn's consoles in the "Base" map.
For Vegetable Guy, just destroy all the fruit stands on the "Market". No matter which weapon you use to do it. I'd suggest a fast firing one though.
For Party Time, Monkin already explained it pretty well. To be more detailed, I'l say that you have to open the first level, jump up to the generator, reach it, turn back without hitting it, and crouch walk past the invisible wall. Then, when you come back at the starting room, jump up past the wall, and proceed all the way to the right.
For Vegetable Guy, it's best to get either the Juggernaut with an elemental weapon or the Mercenary with a heavy machine gun to clear the fruit stands. If they're empty but you don't get the achievement, shoot them both a little more.
For Party Time, you need to wait till you get asked to whack the generator before coming back down. There's an invisible wire you need to duck past to get through. The big red box in the control room at this point will also be passable (you can go through it). Go to the very far right and you should see the party face. Get in the room and you'll get the achievement.
For Game Breaker, get a Tesla Coil killstreak with the Engineer. On a Custom Game in Very Easy mode with max players this should come along pretty quickly. Drop the Tesla right in front of the TV (where the springboards are). This should get Jyn's Xbox to BSOD.
