I was just curious how many legion plan to do either have someone switch permanently to one of the races so you can complete the mission with a high or certain success rate?

We are not and it occurs to me that there are probably few legions that would devote their resources for the badges.

The three that require certain professions are
Carthyne Symposium- requires explorers, physicists, or governors. (cyborgs/skilled genetarr?)*
*Not sure if this is a race requirement or not, never had this one.

Illegal Excavation- requires Hackers, Physicists, or Spies.

Galakis, City of Deals- requires Builders, Fixers, Merchants, or Physicists

So basically a physicist if they were to permanently switch. It requires several not one or two but like 10+ to get a high success rate 15 is what we aim for. I suppose it can be useful for bases if they were Lazuli physicists, but is anyone actually going to get a bunch of them to be successful on all the legion missions?

Personally, I feel it's not worth it. Legion missions have great rewards, including the Relic Badge items, but they aren't a limited resource. They will keep arriving, so failing some (as you can still pass those, granted it seems the race-change tasks carry the greatest success-value in those missions) will only set you back on your goals, as opposed to keep you from ever achieving them.