The kaiju from Pacific Rim can use the Giant Reach and can use the Carry ability with it. Under the Carry restrictions transporters, duos, and fliers can't be carried. It says nothing about giants or colossals. So can they carry each other or is there something in the rule book I didn't find?

because kaiju and jaeger are colossal, and there are not other character bigger that colossals, colossal character that can use carry ability can carry any character if the character you are trying to carry is a single base and don't have any , , , , , , symbol,

Can they carry each other though?

Carry clearly states which characters can't be carried(see quote below). As long as a character is/has none of the listed things it can be carried.

The pacific rim characters are all colossals and they are all single based so that leaves just the symbols to prohibit them from being carried.

All the jaegers have: so they cannot be carried. Of the kaijus its only Raiju that cannot be carried as it has .

They can be carried, but only by other characters their size or larger and as long as they don't have any of the Combat Symbols as listed by others.