Walkthrough. All Bonus Objectives, Intel.
There's two ways to do this mission.
There's the really, really easy way. With this one you avoid fully repairing the Catalyst Missile building until you've built a ton of Avatars, then you finish the repairs and destroy the Scrin before they have a chance to do anything.
But I think that's not the intended way to complete the mission, and so I've opted to show how to beat it in what I believe is the "intended way".
So, we send our initial forces over to the green base. We Rank up the Bikes using the crates to give them the self-repair ability, and use them to defend and escort the Saboteurs to the green base.
We cap the Construction Yard, which captures the entire base meanwhile we're building Refineries, a Tech Center and War Factories.
Once the Catalyst Missile building is repaired we make short work of the South East Scrin base.
Then, while defending our own stuff we build a buncha Avatars.
When the time is right we send our Avatars and South Tanks to destroy the remaining two Scrin bases, completing the mission.
I hope this helps someone out!