by PROJ
If the gaia scoring is favorable enough that terrans would dominate, think about the ramifications:
This means that terrans *should* be picked first, since the first person to pick race should be optimized to score the highest without interference. This means they will have worse access to favorable round boosters.
Most setups favoring terrans would also necessarily favor the other two heavy gaiaforming races: the itars and bal'taks. Granted, not every map is going to be favorable for all of them, but a good chunk should be.
The default gaia planets on the map are meant to alleviate the gap between gaiaforming specialist races and the others. You have to focus not necessarily beating the terrans at obtaining gaia planets, just keep up so they don't have an insurmountable lead and overtake them elsewhere.
Terrans also struggle to gaiaform a lot and get a lot of navigation simultaneously. You can take advantage of this by cutting them off if they go early into the gaiaforming track, or keeping up with their gaia planet colonizations if they go towards a PI build.
There's also several races that can gaiaform pretty well at level 1 in a pinch. Ambas, taklons, and bescods come to mind. You can also take advantage of gaiaforming depending on the timing of power charges and whether or not the +2pt round booster is in the game.