Credentials for criticism below: I'm a diamond 2 jungle/support main and I have over 100 games of Jarvan IV - I also did some quick extra research on probuilds

21/9/0 > 9/21/0. It increases your clear speed massively and also means you're a lot bigger of a threat both in ganks and early/mid game fights.

While the golem path is viable, Lizard is definitely the dominant option to go for, especially solo queue. You will lack tankyness early game but you can make up for that by not going for ******ed engages and getting tanky items after this.

I'd personally recommend running at least a few armor pen marks due to its natural synergy with Jarvan. Some magic resist in runes are helpful as well, although that's quite optional.

Locket vs AD based team makes absolutely 0 sense at all.

There is absolutely 0 point in uploading unfinished guides. I would advise you to archive this and upload it again when it's 100% finished.

It's pointless to make builds vs AD and AP based teams, it's a lot better to structure your builds like this:

Core items - items you should get in every game
Snowball options (when ahead) - damage items
Defensive options - tanky items

This means people can pick the items they need in every situation and also means it's a lot easier to understand. There is no 'one' optimal build vs an AP team or AD team, and it also doesn't explain what to do vs balanced teams.

Also, if you really are platinum you can get yourself verified on this site.

Never published unfinished guides (except maybe just matchups are missing)
Still worth mentioning Spirit of the Elder Lizard when "snowballing".