Neoverse

How to do this is on paper is very easy, just don't spend any money in the shop. The mental easiest way to do this is never even open the top shop (the gold icon like a wagon in the top right of the screen), I can confirm that you can actually open it and not spend and still get the achievement if you do accidentally.

That does cut out a key part of the game so there are a few things you can do to maximise your chances of success.

1.First of all, play this on Transcended level 0, no need to make this harder on yourself (if you're just starting the game, this is the base difficulty).
2. You can still use items so don't be afraid to use them, generally speaking you'll want to save these for boss battles but if you have a mission you're going for that an item would help you get a chance of getting the rewards that's worth it too.
3. Skill points are fair game too, its a bit rng which ones you get but of particular note the ones I found specifically useful were: Recover 30% HP before a boss (and its upgraded version 50%), and 'backpack' which is +1 Item space, its also cheap at 2 skill points. I also really like anything that leads to giving you force like 'upgraded force suit'.
4. Missions are fair game too, play to your strengths, because we couldn't use the shop, I went for upgraded cards and skill points, if you ever see one for a 'super ultra capsule' that's often worth it too.

I used the summon's deck Helena but I think you'll have an easy enough time with most of them with some planning. My general biggest piece of advice is to get a combo ready for your highest attack card, double damage is not to be sniffed at.

Good luck, any improvements to make on this let me know.

Like a Bob Ross also recommends Helena:"Helena makes this easy.

Prioritize mana skills and constant cards."