Anyway, here is what non-Mook suit GUNDAMs are capable of,and this is 00 which has pretty weak mechs as compared to the rest of the Universe/Multiverse/Metaseries/whatever:
Turn A gundam for instance is powered by a black hole and can deploy nanites that regenerate it and can destroy all technology in the solar system from earth all over to Jupiter.
Won't help. Godzilla's soaked direct hits from Black Holes and the black hole was destroyed instead of him, such as his fight with Megaguiras. Void Ghidora actually overpowered a black hole and climbed out from inside one. Black Holes are the lowest point where you get a seat at the table to
start fighting Titans on the weakest rung, not a powerful super-weapon against them.
Note the dialogue of the movie states that the black hole weapon is
guaranteed to destroy the earth unless they land a direct hit on Godzilla because his body will soak enough of its destructive energy that Earth can survive if it hits him first. Godzilla is literally established to be
tougher than the entire planet.
The vast majority of these lack the size and firepower to engage Kaijuu. Battletech 'mechs are also slow compared to the others and going to wind up crunchy speedbumps. Same for most Gundams and Exo-Squad. A few of these universes have actual firepower to fight Titans but ironically will also destroy the Earth/cause massive damage in the process because they don't have a way to dial it down to the proper level. Robotech/Macross are in this situation, a Reflex Cannon is a planet killer if they hit the earth with it and a Valkyrie/Veritech is a crunchy speedbump (albeit fast enough to never get stepped on), with not much in the middle ground that can both fight Kaijuu and not ruin the world trying. Gundam Wing has the same problem, the Busters are powerful (albeit popguns at the Godzilla level but at least they could be annoying) but everything else won't matter.
Pacific Rim have the actual size and power needed to go toe-to-toe with Kaijuu but not really the level of BS needed, such as the aforementioned "it can soak a black hole" feat. They will make a good showing and can theoretically win depending on how the numbers and support roll out, so long as all their funding isn't pulled to build a pointless wall. Overall, they probably just can't throw down enough raw firepower to overcome the regeneration and hax Titans have.
Voltron can solo the Titans, it's not only large enough but has some obscene kill feats and is actually equipped with weapons like the Flaming Sword that let it do enormous damage to a single large target without doing enormous damage to all of Tokyo in the process. Anything less than magitech just flat out isn't going t work, though.