What would this forum consider as the current list of essential software to study theory, gameplay, scenarios, mixed strategies, etc? This would be my best guess but I am curious what the forum thinks:

pio
CREV
equilab
poker tracker

Also what is the best verion of Pio to get? Is the basic good enough or are the 'pro' or 'edge' versions better.

I am new to 2+2 I think maybe i should have posted in the 'software' forum.

Depends on what your goals are/ how good you are/ which stakes you play.

I don't think it makes much sense to buy both pio and CREV, since they do a very similar thing. Overall, they aren't as useful as one may expect, since most strategies are very mixed and predictable. For example, on most flops 90%+ hands will use mixed strategies. Sometimes they will bet small, sometimes big, sometimes check...
Use them if you find them fun, otherwise it seems a bit of a waste to spend 250-1000$ on pio. That's just my opinion.

Trackers (PT4/HM2...) are probably much more useful in the long term and cheaper.
Equilab is free.
I don't think anything else is really needed, just some good logic and experience.

Snowie is another software that is mentioned often.

Power Equilab
GTO+
Snowie
PT

Wouldn't get PIO unless you want to do preflop sims. GTO+ is perfectly fine for postflop and 10x less expensive. Wouldn't bother with CREV either, you can do some interesting exploitative modelling with it but it's extremely time consuming and you'd be better off just using that time to study solver solutions.

PT or HEM for tracking and analysing your results.
(Power) Equilab for rangebuilding and equity calcs.
And then any of the solvers (Pio, GTO+, GTOrb, SPF), or Snowie, for more in depth pseudo-GTO solutions.
I'm a big fan of Snowie, but if I was starting afresh I think I'd go with GTO+ because it's so much cheaper than Pio.