If i activate a counter trap but have no monsters on the field to tribute can i still play voltanis and just not destroy anything extra?

In order to Special Summon him, part of the requirement is to Tribute all monsters on your side of the field.

The secondary part of his effect is only dependent upon the amount of Fairy type you tributed.

Of course, you do not have to Special Summon him. He is still a 2 Tribute Monster from hand. You just wont be able to destroy anything.

I thought that was how it worked but my friend adam keep telling me he could play it without the tribute.

No, you need at least one monster to tribute to special summon Voltanis by using his effect. You can still normal summon him too of course.

no, you can't summon him by his effect without at least 1 monster to tribute, same reason you can't use something like rope of life with no cards in hand, a cost is a cost you must be able to pay it.

Well based on the rulings found on dm comet, you can special voltanis w/o tributes. You just won't be able to destroy anything. So who is right? I looked it up on the official website, but it doesn't say anything regarding it.

No...if you want to Special Summon it by its EFFECT, you MUST Tribute at least 1 monster. And it does say so right on the site...

"Tributing all your monsters to Special Summon "Voltanis the Adjudicator" is a cost. If you do not have at least 1 monster to Tribute, you cannot activate this effect."

...you CAN Special Summon it through other cards like Premature Burial, Call of the Haunted, etc, but since that is not its own effect, you won't have to Tribute anything, but also won't get to destroy anything.