You are talking about two things here: 1) a T0 MG for OKW, and 2) a general game plan for OKW in 4v4.
To your second point first. You will find that OKW in team games benefits strongly from Kubels because they can cover large distances quickly and cap points. You can constantly keep your opponents moving to attack kubels instead of setting in. This strategy works well when another player gets a med truck up and one group does not have to retreat because they can reinforce on the field. You can even skip volks and tech to Fusilliers if you get enough pressure going. I find luchs in team games very unpractical since the amount of AT is higher and you can easily run into two AT guns, spelling doom for the tank and giving your opponents the mid game. The luchs still has a place, and it becomes a beast as it gains vet, but I tend to want callin infantry before I get a luchs. As Cloth pointed out the other option is volks spam all day every day. Volks can, in number, overwhelm Allied starts, especially if they can force off an MG or two.
Having said all this the Allies have a clear advantage in games right now. They have a fairly strong opening which leads to rapid tech to artillery of all sorts and ultimately a very high bleed for German forces. However, if OKW and Wehr can get a foothold they are nearly impossible to control since their late game power can come into the mix and the disadvantages it presents in smaller game modes simply don't exist (limited munitions is not a real thing in 4v4). The German team should be content to holder smaller amounts of the map and build out from there. I would strongly recommend the use of JT in all 4v4 games. You should also have a command panther, and a fortifications commander available in case of brit emplacements. I would also consider the SturmTiger as a strong choice.
On the MG, that is a bit tougher. OKW needs a more complete rework and I think moving the MG to T0 is possible but with current OKW it would be too punishing early for Allied infantry facing off against cheap spammable volks.
