If you download coolbooter now, and not find iOS 5, you should follow this guide.
First, Jailbreak your 9.3.5 ipad with phoenix. You have to install the Phoenix ipa from here
then you have to use a tool like Sideloadly to restore it.
Then, downgrade your iPad with iOS-OTA-Downgrader to 8.4.1 here is the link.
If the instructions are not clear enough for you, you can watch the first few steps of this video. DO NOT install dropbear or add the repo because you are not on iOS 10. and DO NOT follow the steps to downgrade to iOS 6.
after your ipad is downgraded to 8.4.1, jailbreak it with etasonJB. for me i didn’t see the repo packages come up (on iPad2, iPad mini, and another iPad mini) so as soon as you see the pop up Complete Upgrade, DO NOT CLICK later. click complete upgrade. if not, you might have to redo step 1 and 2. go to sources and add repo http://coolbooter.com. click coolbooter, modify, then downgrade, then 1.4. click continue queuing. now go back and click coolbooter untether. click modify, then install. now click continue. after it installs click on Restart Springboard at the bottom. go into the new app called coolbooter. now click install, select whichever ios 5 version you want, click on storage at the bottom, select the maximum possible. click start and follow the onscreen instructions. You now have an iPad 2 on iOS 5. great job. if you want to install gmail on your new iPad 2, check this guide. Have a nice day.