Do u have to collect all the stamps to get 100% and finish the game?

what do you mean by stamps

well, I don't have all the stamps yet. I haven't bought all of them too, but I have 91.4 % so I am almost finished.

I think you need to battle online so you can get every stamp available in your game. I don't have them all in my shop just yet, but that will change.

Yeah you need all the stamps to get 100%. But you don't need to fight in Network Battle to get all. You just need to:

Beat Arcade with all difficulties, and until you can't get anymore at the end.

Survival at least 25 wins

All Time Attacks (I believe there are no fixed time needed)

Dragon Road with all Z ranks.

quote Zejitox

Yeah you need all the stamps to get 100%. But you don't need to fight in Network Battle to get all. You just need to:

Beat Arcade with all difficulties, and until you can't get anymore at the end.

Survival at least 25 wins

All Time Attacks (I believe there are no fixed time needed)

Dragon Road with all Z ranks.

Most of this is correct, except there is Specific times for time trial, 2 grades of time to beat, the 'Z Times'(Very good times) youve got to average about, 35-40seconds per fight. Then the 'A Times'(easier to get), which is average of under about a minute. You can get both at once, which you'll notice if your good enough.