Are there any special signals for Giovanni to sort him out from decoys?

I searched 3 rocket leader signals and haven’t found the real Giovanni yet.

I’ve also heard that his signal is a “G” instead of “R,” although I cannot confirm that.

I faced Giovanni last night and didn’t notice any differences between the stop that he was located at and the ones with decoys. However, the stop that Giovanni is located at will be the same for all players that day. I was finishing up the questline last night with a friend who was just slightly behind me in progress. I checked 5 stops (and battled 5 decoys) before I found Giovanni. When my friend got to that stage in the questline, he immediately went to the stop where I battled Giovanni and sure enough, he got Giovanni as well.

So if someone in your local group reports Giovanni’s location, everyone needing to battle him that day can take advantage of it if they don’t want to put up with the decoy battles.

Note: Decoy Grunts will still drop mysterious components, so it may be worthwhile not to skip them. You are able to collect mysterious components for the normal Rocket Radar even while your Super Rocket Radar (for finding Giovanni) is active.

On the Radar he appeared exactly the same as every othter stop, lucky enough I only had to go through one decoy to find him but the stop even when you reach it appears to be the exact same.