doing the one to wave 30 is easy using a second controller sitting idle on space station, at the top of the stairs there is only one way in and you can defend it easy using stewie's magna gun and just fire it into the doorway at the bottom of the stairs, you can use the portal store behind you and just enter and then leave the store in one quick move and it fills your bullets and grenades, there is also a health pack there around the corner too.
remember to put the second controller near the portal store so he doesn't get hit as much.
inbetween the rounds you can go out and pick up items to use if you want but i only ever used them on the last wave just to use them up.
so just use the magna gun then throw 2 grenades in and use the store/leave then back and repeat, just keep doing this, the robot chickens take longer to kill with the magma gun but it will kill them but use grenades.
i did it on my 1st go.
no doing the challenges for me has been a nightmare even trying a second controller isn't helping, the money shot one im still stuck on due there being a timer.