The outstanding example in my mind is from a low-budget circa 1960 movie called Dinosaurus, which featured some decent stop-motion animation by guys who went on to do The Outer Limits. They had to cut some corners (for several scenes they used puppets instead of animating things, to save time and money), but the results were still being recycled years later on TV shows.
The premise is that a T. Rex, a Brontosaurus*, and a Neanderthal (consistency? We don’t need no stinking consistency!) get pulled from frigid waters off a Caribbean island**. They’re perfectly preserved, and get revived by a strike from a lightning bolt. Hijinks ensue, with the T. Rex threatening and killing folks, a boy befriending the brontosaur, and some slapstick from the Caveman.
Eventually they confront the T. Rex, and the Hero does battle with it by getting into the steam shovel that originally excavated them from the water, enabling him to fight it off mano a mano, or at least as mano as you can get with a T. Rex’s stubby forearms.
Our Hero manages to topple the T. Rex back into the frigid waters, saving the day (although the bronto and the Caveman had also died). I’ve long suspected that James Cameron saw this film, and was inspired by the T.Rex/Steam Shovel fight to create the epic battle between Ripley (in the Loader suit) and the Queen Alien in his 1986 movie Aliens, which is another example of the trope the OP asked for.
As for actual tanks doing any good, I honestly can’t recall a case where they were depicted as being completely useful. In all the Toho kaiju films they seem like window dressing – you trot them out, but the monsters virtually ignore them. There’s one in Caltiki, the Immortal Monster, but it isn’t shown actually confronting the blob monster in that film, and it’s not clear what good it woulds be. Gort pretty famously melts the tanks arrayed against Klaatu and his flying saucer in the original Day the Earth Stood Still. They used artillery (although not tanks) against The Beast from 20,000 Fathoms, but had to stop because its blood was making everybody sick. The Giant Behemoth strikes down his antagonists with radiation before they can do him any harm. The valiens in Earth Vs. the Flying Saucers, like the later ones in Independence Day, are safe behind their force fields, so artillery is of no use.
Interestingly, non-mechanized bazookas and other hand-held devices are shown as effective in these films – Reptilicus is brought down by a poison-filled bazooka shell to the soft lining of its mouth. The Beast from 20,000 Fathoms was brought down by a radioactive shell from a grenade launcher. A home-built bazooka turns the tide in World Without End.
Submarine torpedos are effective, too. One brought down the giant octopus in It Came From Beneath the Sea, one took out The Giant Behemoth, and another got the alien menace in Atomic Submarine (a virtually forgotten 1950s film by some of the folks responsible for Forbidden Planet)
There’s no reason nhat a tank couldn’tbe used to good effect against you giant monster/alien menace. They’re awesomely destructive and tenacious. There’s good potential there for some filmmaker.
*This was the 1960s. We still had Brontosaurs
**This always bothered me, even as a kid – frigid waters in the Caribbean? Best to just go with the flow, though.
