In my fifth game, the Telaskims of Zolan game (the one I spent the most time developing), I would up at war against the Grox around when I got badge level 10. They did manage to wipe out the colony of one T1 planet twice, but they weren't so lucky elsewhere.
I made it my business to have it where just about every colonized celestial body in my empire would get to Terraform level 3, be maxed in cities (and stuff in them), and have uber turrets (among a few other things like Bio-protectors). Although playing at Easy may have helped, these planets were so heavily defended that they stood up against Grox raids (with out my help) and won time and time again. Even if I'd have to visit some time afterward to replace lost structures.
Soon I took the fight to the Grox, carving huge chunks of territory away from them. Strangely, systems that once belonged to them started gaining intelligent life, albeit Tribal and Civ-level. So I got some monoliths and started to uplift them. I used them for recharges and reheals. I'd go to a Grox system, destroy the cities, then return to one of the uplifted empires for repairs and recharges. It would've helped if there weren't uncrosseable gaps on my way toward the core, though. They were a pain to try to go around.
I soon realized that the ability of my planets to handle the Grox on their own meant I could go where I please, even during a Grox raid on one of my planets. Or even colonize planets encroaching toward Grox territory. I started with making colonies at other ends of wormholes leading deep into Grox territory. From there I could hit-and-run my way to the core. Which I did.
Some considerable amount of time later, while looking for Earth (I'm still looking, by the way.) I decided to return from checking damage at another near-core Grox raid. Except I flew my craft toward the core by mistake. When I got there, I made a decision: to take out the Grox installments of the closest star system to the core.
The third city I captured instead of destroyed. I now control the single closest star system to the Galactic core.
I proceeded to set up six cities on two planets right away. (Then I ran out of colony packs and would have to wait or something to make more cities.) But soon enough, I got more of those packs and took control of the next to systems closest to the Core.
By the way, whenever I play another Spore game, one of the fastest means of getting rich is to reach the Telaskim empire and trade spice like there's no tomorrow. ^^
I now wonder: what happens if I manage to completely wipe out the Grox?