I saw a few episodes of this anime series between 1986 and 1990, and it was on during childrens shows so it was definitely directed at children rather than adults.
The plot lines I can remember are floating alien space ships over earth cities, alien robot mech suits fighting with human piloted mechs, human hover style tanks working with the human mechs in combat.
In one episode a scientist postulates that the enemy ships can be disabled by hitting one very precise spot on the ship with a shot from a tank - for some reason he goes along on the attack in the back of a tank, but in the middle of the attack he is grabbed from the back of the tank by an alien mech (kidnapped, killed, unsure). The attack goes ahead, the spot is hit and it does nothing.
Another episode involves a group of human piloted mechs that manage to get inside one ship and explore it, while being periodically attacked.
Another plot point is that they discover the alien mechs are not robots but actually remotely piloted, and the remote pilots can feel pain etc due to the way they are wired in - the humans elect from then on (for some reason) to only deliver disabling shots.
Thats pretty much all I can remember.