This app was mentioned in 7 comments, with an average of 1.14 upvotes
Other scanners (e.g.) store a list of Pokémon. You can add HP/CP/level snapshots to a Pokémon to further narrow it down, rather than only narrowing based on the previous and current scans. This is demonstrably superior to a system which only allows two snapshots and personally I would like GoIV to support it. But apparently I don't want it enough to write and submit a pull request, so…
Edit: added link
I use the cleverly-named "IV Calculator:"
https://play.google.com/store/apps/details?id=com.dancmc.ivcalcgo
It has a nice toggleable Overlay that you can tap/hold to give it transparency. I like it.
What lazybum said, or use an IV calculator app that allows narrowing down the results with Appraisal info, such as this one that I'm personally using: https://play.google.com/store/apps/details?id=com.dancmc.ivcalcgo
That one supposedly has accurate info and I've understood it's somehow related to SilphRoad, so should be accurate at that. It's also nice and easy to use.
Edit: looking at that Eevee with my calculator (the above) shows the same possibilities. It says the lowest 66% will have 14 attack which at that is pretty good. 70something has 12 which is lowest of the possibilities while other two have attack of 13 and 15. Stamina I think was at least 9 on all while defense changed from 7 to 14.
I really like this one. It looks nice, plays well and most importantly the stats are quite accurate.
The thing is somehow affiliated with TheSilphRoad or so I've been led to believe.
Take a look and see if it's to your liking.
https://play.google.com/store/apps/details?id=com.dancmc.ivcalcgo
Afaik, 200 Stardust won't affect the level, but might be mistaken.
Having the dot on the left end means it's lv1 though. Each power up you do increases the level by 0.5, not 1.0 as one might expect.
As for the stats like Attack, Defense and Stamina being accurately shown it depends on things. Doing an IV calculation with Appraise info often manages to narrow it down to pretty few options only.
IV calcs are plenty and some suck big time. Pokeassistant is said to be the better and more accurate one as well as silphroad stuff.
The one I'm using is pretty good and simple enough to use. Here's a link to it: https://play.google.com/store/apps/details?id=com.dancmc.ivcalcgo
The overlay stuff is pretty horrid to use though and I prefer to enter stats by hand.
Edit: As for the bubblestrat it depends on so many different stuff and every little 0.1% in IV counts, twice, because you have attacker and defender in there. Like someone already said most of the time you can't tell for sure, you just have to try powering up and see if.it works.
I managed to screw up once with Squirtle. It became too strong so I didn't get the full 1000 prestige, only managed to make it work with stronger attacker that gave 625 prestige.
Later on though I managed to find a proper Horsea that works perfectly with my Gastlys.
Oops sorry I've been so insanely busy with my day job I haven't seen my messages. It's still up - https://play.google.com/store/apps/details?id=com.dancmc.ivcalcgo
Wierd. IV Toolkit says my Charmander is a 55% but with this, it says 62%