It was bound to happen. Someone has taken clips from Guillermo del Toro's PACIFIC RIM and edited them with clips from Gareth Edwards' GODZILLA to bring us the ultimate Jaeger vs. Kaiju mash-up with PACZILLA, and it is pretty damn awesome. Considering both films were produced by the same people (Legendary) and released by the same studio, I'd totally plunk down the cash to see a crossover. But since the chances of that happening are pretty slim, we'll just have to make do with mash-ups like this one below.
By the way, my money would be on Godzilla to kick some Jaeger ass.