Oh the multi edition rule confusion... do it all the time to the point we drew on the table a list of common rules mix ups(we custom built a table with built in sockets out of an old table we just slapped some chip board on top)I just found out yesterday that getting advantage from just being adjacent is optional rule (with only one barbarian totem getting it normally) - what I remembered was a combination of 3.5 and 5e things:
3.5 rogue needs flanking for SA and 5e explicitly stating that rogue needs only an ally adjacent to a creature to get SA...somehow, I mixed up those two.
So, for the record, you can grant advantage IF YOU SPEND ACTION to aid a companion. Even being in true flanking position gives no bonuses (unless optional rules are used or DM rules otherwise)
Sorry for any confusion I caused.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.