In chapter 1 it starts off with a metal hippoe follow by some more after about 20 seconds with weak peons thrown into the mix. After a bit a lemurr spawns and the rest is unknown to me as I beat it then
chapters 1 and 2 are pretty similar, with the only difference being Cyberhorn. It is possible to speed run chapter 1 if you have crazed cow as you can spam that and Valkyrie to easily kill the base before the lemurrs cause too much damage Use your regular team and you should be fine, take extra caution of the Lemurrs and Cyberhorn however.
Chapter 3 is basically elder sloth + peons and lemurrs. Keep on meatsheilding and use longer ranged attackers to chip down that ugly sloth.