Downloaders
Pixiv
By download button on a pixiv work on chrome https://chrome.google.com/webstore/detail/pixiv-tool/midohckdddplmkihkkdaacbjpmgkjbhk
By batch/commandline https://nandaka.devnull.zone/tag/pixiv-downloader/

Deviantart
By work page, click the icon in the Chrome toolbar https://chrome.google.com/webstore/detail/deviantart-downloader/kdcokocnkphjbaelobcehjokdleflnmj
Jdownloader to grab entire galleries http://jdownloader.org/download/index You should pick 'Other/java' as the others might still have adware bundled

VK
Use Jdownloader

Danbooru
https://nandaka.devnull.zone

Tumblr
https://sourceforge.net/projects/tumblrimagedown/

Finding tags: japanese or otherwise
1. Open up your bulbapedia page for your character http://i.imgur.com/zzgDuZm.png
2. Copy and paste the name into your site of choice eg twitter or pixiv