I was not able to get Explosive or Cold Biters to generate when also using Kraztorio 2. They do generate if I enable "vanilla biter generation" in startup settings.

I would need to check. If they are in standard spawners they should work. If not then I will need to add new spawners to generate them in RSO.

Do you know how to get those to spawn in vanilla game?
I grabbed Krastorio 2 and I don't see any new biters. Are the biters in some extension to Krastorio?

They're from:
https://mods.factorio.com/mod/Cold_biters
https://mods.factorio.com/mod/Explosive_biters
Which are sorta-recommended by Krastorio 2 (K2 recommends all mods by Earendel, and his Alien BIomes recommends both those mods.)

Same here, still not able to get cold and explosive biters (i dont even use K2)

I will try to take a look - RSO support for adding more biter types is a bit less developed then for ores.
And thanks for thre remainder thread fell through and I forgot about it.

I've added support for both mods in new version.
Please be aware that RSO doesn't support some special placement options - so with RSO new biters can apper anywhere on map. In original mods they have special rules that spawn them in cold biome only for example those won't work.
You can get original functionality by changing RSO settings to enable vanilla spawning and disable RSO biter spawning.