okay let me clarify Chronojet Dragon can be a vanguard in fact all of the cards in you deck can be a vanguard because they're all known as Units the only exception are your grade 4 units which are known as G-Units. If I'm correct they go into a separate pile from your main deck of 50 cards. When starting the game both players choose one grade 0 unit to be their vanguard this unit typically wont want to have a trigger emblem n the top right hand corner. As the game progresses you may Ride a new unit on top of the old one The new unit must be either one grade higher or the same grade as the card its going on top of. Then there's the Generation Stride which I still don't fully understand so I'm not going to explain it here

EDIT: Also I have a question....When performing a Twin Drive/Triple Drive if you get a stand trigger and stand your vanguard and attack again do you get another Twin Drive/Triple Drive? I would imagine that's how it works but i want to be certain.