>>7980341as unintuitive as it is you could make an argument for Monster Fighters taking place after Hidden Side, since Monster Fighters ties pretty much directly into Galaxy Squad, which seems to clearly take place after Hidden Side (and as a bonus Ultra Agents then takes place after Galaxy Squad). Though you could also argue the insect aliens are just really really slow in getting to earth.
Really though I doubt there's this much thought behind it and either deciding MF is happening somewhere in the late 18th/early 19th century or all are happening alongside each other seems the best version.
