Saints Row IV

To complete this achievement, you need to purchase all of the upgrades for your super powers available to you using the clusters you collect in the world. Of the 1255 clusters in the world, you only need 1065 of them to unlock everything - if you've collected all of the clusters, you should have 190 of them remaining once it's all said and done.

You do NOT need to earn all of the powers that you gain by completing challenges. This achievement popped for me while some were left unlocked, so you should be fine.

All that being said, many people are reporting this achievement to be glitched, so you may run into some issues with this one. If it's helpful, I unlocked this achievement under these conditions:

-Having already beaten the game
-At Level 50
-Completed all quests and loyalty missions
-100% completion of open-world activities
-All collectables collected (all clusters, audio logs, statues and text adventures)
-All challenges NOT completed. I still had powers locked away as challenge rewards.

It is worth noting, as has been mentioned in the comments, that no matter what you do, you cannot unlock this achievement until you've completed the mission "The Kinzie Gambit" - the last of your powers are locked by progression until you complete this one.

Best of luck, and if there becomes a clear solution to how to avoid a glitch, I will update accordingly.

First and foremost, this achievement is glitched (as of September 2020 anyway, and it's been out since 2013 so I'm assuming it ain't being patched). Thankfully, there is a workaround.

I thought it was worth leaving a solution specially for those who have had this achievement glitch on them, since I had to dig through comments to find out what to do (including some conflicting information), and also wanted to add my own two cents. This solution assumes you've already beaten the game, should've popped the achievement, it hasn't popped, and you've come to TA to find out why. So:

1) Start a New Game (on Casual of course). Just play story missions, nothing else, until you beat the level "The Kinzie Gambit". This is about 3-4 hours in. Once you've beaten this mission, stop playing story missions. For some reason doing so will glitch the achievement.
2) Play the side mission that unlocks the collectible finder. Can't remember what it's called, but at this point in your game you'll definitely have unlocked it. It's a Matt Miller mission.
3) Reach level 50. Playing side missions is probably the quickest/easiest way to do this, but there's also an outfit in Planet Zin called "Zero Saints Thirty" which you can buy as many times as you like; it costs 1700 credits and awards 200XP each time. You can also play Activities to get XP. Also, any non-cluster collectibles give XP, so collect any that you pass that are easily accessible.
3.5) While you're doing this, collect any clusters that you pass (marked on your map thanks to the collectible finder from step 2). I would recommend completing "Towers" first because climbing to the top awards XP and there are lots of clusters on the way up. Also along the way, make sure you're buying upgrades (especially XP and cache bonuses) but make sure you don't buy any power upgrades. From the back button menu (with Map, Quests etc), anything in "Upgrades" is fine, just never click on "Powers".
4) Once you're level 50, collect any more clusters; you will need exactly 1065. There are significantly more than this in the game, so if you're struggling to find/access any, just move on. There are enough easily accessible ones to go around. Also, on the map, they don't appear by default even with "All" selected, but if you scroll down to collectibles they will appear. You don't need to do this to make them appear on your minimap though; once you complete the side mission in step 2 they will always be there.

Once you've completed these 4 steps, you're level 50 with 1065 clusters, go into the "Powers" menu and just buy absolutely everything. The achievement should pop!

A few things to note. Firstly, don't panic if you get to the buying Powers upgrades stage and there are a couple that are locked (with the message "Complete challenges to unlock this upgrade"). This happened to me and the achievement still popped. This is because technically these upgrades can't be "purchased", they have to be unlocked (and don't cost any clusters), so therefore they don't count towards the achievement description. If you're level 50 with 1065 clusters, you'll be able to get the achievement.

Secondly, when I did it I did step 3 and step 4 in reverse (went around collecting clusters first, then focussed on levelling up). I wouldn't recommend this way. Most of the side missions involve plenty of running (or driving) around, which means you're often going straight past plenty of clusters. Either way is fine of course, but the way I've listed above will take less time. My way took 12.5 hours according to the in-game timer, so I guess the way I've listed above will take between 10 and 12.

Thirdly, I'd highly recommend having a podcast or something to listen to at the same time as playing. I absolutely love the humour in this game, and enjoyed replaying all the story missions, but when you're just doing side missions/activities and running around collecting clusters, something to listen to at the same time really helps it to not feel like a massive waste of time...