http://www.youtube.com/watch?v=Ssftz10SXZQ
The video makes things go along faster then me explaining a merge to you all. The video is from episode 1.

Above are all the vectors with their name underneath and their Aquarion merges. Later in the anime different vectors are brought in creating different Aquarions. Pictures will be posted of those and their vectors soon. (Hopefully)
Vector 1: "Merge One"
Vector 2: "Merge two"
Vector 3 (Head): "Aquarion!"
What you say before either or those lines depending on the merge formation doesnt matter like you noticed in the video above.
There are three vectors like you read above, Vector Sol, Vector Mars and Vector Luna. They each create three different giant mecha's with the same name depending which Vector takes the lead when merging. Merging is when the three vectors and the three controllers create a triangle in which the one at the top of it is the head element. Who ever is the head has main control over the vector.


