Copied from Reddit because I hadn’t seen anything about it on here yet. Link is to original posting

    Hey everyone,

    I wanted to take some time to clear up some misconceptions about Island Scan and provide a list of which Pokemon appear at which time. I have seen a lot of websites that detail how to use Island Scan and provide a list of QR codes to scan, so I won’t do that here. I’ve even seen one outlet claim they found a Bulbasaur in Melemele Island.

    But here is a list of every Pokemon you can collect while using Island Scan:

    First, you need to boot up the Island Scan from you ‘X’ menu and scan QR codes from various sources (here is all the QR codes for every Pokemon https://imgur.com/a/EFOqs).

    Next, scan ten different codes to start finding new Pokemon. You can only scan 1 QR code every 2 hours but you can bank all ten codes to use at once.

    Here is a list of all Pokemon found, where they spawn, and which day they can be found on:

    Melemele Island:

    Monday: Totodile in Seaward Cave

    Tuesday: Deino in Ten Carat Hill

    Wednesday: Horsea in Kala'e Bay

    Thursday: Klink in Hau'oli City

    Friday: Chikorita in Route 2

    Saturday: Litwick in Hau'oli Cemetery

    Sunday: Cyndaquil in Route 3

    Akala Island:

    Monday: Spheal in Route 7

    Tuesday: Luxio in Route 8

    Wednesday: Honedge in Akala Outskirts

    Thursday: Venipede in Route 4

    Friday: Bellsprout in Route 5

    Saturday: Marill in Brooklet Hill

    Sunday: Gothita in Route 6

    Ula'ula Island:

    Monday: Swinub in Tapu Village

    Tuesday: Duosion in Route 16

    Wednesday: Roselia in Ula'ula Meadow

    Thursday: Staravia in Route 10

    Friday: Vigoroth in Route 11

    Saturday: Axew in Mount Hokulani

    Sunday: Rhyhorn in Blush Mountain

    Poni Island

    Monday: Conkeldurr in Poni Plains

    Tuesday: Togekiss in Poni Gauntlet

    Wednesday: Leavanny in Poni Meadow

    Thursday: Serperior in Exeggutor Island

    Friday: Samurott in Poni Wilds

    Saturday: Emboar in Ancient Poni Path

    Sunday: Elektross in Poni Grove

    This is all info taken from the guide so if you’ve found anything different feel free to let me know. Also, if anyone has any questions you would like answered from the guide, just ask.

    Edit: /u/Pf9877 suggested to put this link in the body: http://randomqrcode.com/ provides random QR codes that you can use as well.

    Edit 2: Here are some additional tips from /u/Exotopia

    1) you have 1 hour to catch the pokemon starting from when you initiate the scan. Make sure you’ve unlocked the entire island because it can appear in a place you haven’t unlocked yet.

    2) If you island scan and then save, your time will continue to tick down from the original scan time even if you soft reset. In other words, let’s say you scan and save. You reset your game 10 minutes later to the save point. You will now only have 50 minutes to catch the pokemon.

    3) you can save before you scan. If you reset to the save you get your points back and you can scan somewhere else.

    4) the pokemons stats are not set in stone after the scan. You can still reset for gender, shiny, nature, etc. I scanned a serperior, saved, and reset to the save point until I found a female. (in retrospect this was a bad strategy, I should have saved before I scanned so that I would have more time)

    Edit 3: /u/little_red_hat mentions you can scan Special QR codes for 20 points each allowing for 2 Pokemon per day: http://imgur.com/a/BhEhM