let your ally do the left three, and go to the others by yourself, (YOU NEED TO DESTROY THE FIST ONE FAST OR A BIG AMOUNT OF TANKS COMES ROLLING TO YOUR BASE) the best way is to destroy it with airplanes but if u are fast you can also do with flak troopers.
OR, you can take the war factoys an the big power plants so you can build hammer tanks ect.
then the second base is full with garrisonned structures you can easly defeat it with athena cannons but they need anti air support because the next base is the airbase.
then, (while destroying the bases) build a chrono sphere, when it is ready chrono mirage tanks and ati air to the base and destroy it.
(USE NO JAVELINS BECAUSE THEY ALL DIE IN THE CHRONO.)
(if you cannot chrono to the base let a plane fly over it, then you must be fast but you will be able to chrono.
then do the same wit the last base (chrono) and the vacuum imploder
!do not build a proton collider before you destroyed all bases, because if you do he will come immediately with all his forces!
then, the best way to destroy the shuttle is by letting VERY MUCH heavy bombers or vindicators destroy it (and your proton collider)
TIP: when you destroy the bases the ore mines will be left over there you can take them after you destroyed the bases.
if your teammate hasn't destroyed the other bases yet you must first help him