if you flipped it upside down it would look like a heavy-tank version of the striders from War of the Worlds
but as it is, I'm a little confused. It supposedly clings to cave ceilings, which is all well and good, but there are no cave ceilings to be seen in the battle scene. Or even any ceilings at all. Hell, you never see any undersides of roofs in the entire Pokemon series! I guess it's just as nonsensical as Water-types just kinda floating as if they were in the water, but at least I can see visual proof that water does, in fact, exist in the Pokemon world. Ceilings? not so sure.
Hanging around like that also takes away Ferrothorn's cool spinning animation, which makes me sad. I just wish they didn't even bother with these tentacles, they make no sense and only make things worse. But then it would just be a larger, squished Ferroseed. Maybe add some more plate armor to it? then it'd look like Forretress.
maybe there is no answer. Ferrothorn is awkward and alien no matter what you try to do with it.