Hm.. I don't believe either side is really 'right' or 'wrong' in this. It all depends how experienced the beamspammer is. If an average newbie is beamspamming, then it's really no problem.
Now, myself.. I'm more of a melee user, unless people repeatedly try to 2vs1 me, or someone else is continually beamspamming. By using SSJ Goku and abusing beamjump, you can pretty much beamspam indefinitely, and there's absolutely -nothing- your opponent can do about it. If they're the blocking type, detonate it before it gets to them. If they always beamjump? Fire the beam from above them, and follow them with the beam--they won't escape. Teleporting? Not going to do anything against SSJ Goku's fully charged Kamehameha. Swooping? Same thing.
Especially since SSJ Goku can teleport while charging, an experienced beamspammer using him is nearly invincible. The best way to 'counter' someone doing this, is doing it yourself, and not letting them transform.