edit: Jeez, didn't know I wrote that much, lmao.
I never meant for this to become an argument over which game is better. However, as someone who has played many competitive games, I do think that Brawl has a lot more depth than Tekken. The inherent structure of the game lends itself to more depth. In Tekken (and almost all other fighters) you plug in pre-programmed button inputs and your character performs a pre-programmed combo on your opponent. The game plays out EXACTLY as the developers intended. No matter who plugs in the inputs, the results will be the same, and they will look the same. In Smash, the person behind the controller plays that character in a way no one else does, because there are so many more levels of depth to the game. Tekken is limited by stage boundaries. You cannot deviate too far away from the ground you're standing on, be it vertically or horizontally, and all stages are basically the same. Brawl does not have the same limitation. Brawl has more legal stages than I can even think of and each of them changes the playing field dramatically. You can reach all corners of all stages in Brawl, even underneath them if you chose and you actually need experience on a stage in Brawl to win on it. In Tekken, the stage is eye-candy. In Brawl the stage is a weapon that you can manipulate to your advantage.
The most profound difference between Tekken and Brawl is each games goal. In Tekken, the goal is to widdle down more of your opponents health than he does to you. There is no other way to win! Brawl is on a whole other level of depth than Tekken for two reasons: #1. You can kill someone by knocking them off the stage, but if someone is knocked off the stage, any of the 35 characters they would be playing has their own unique recovery game. But, every character also has their own gimping game. #2. In Brawl you don't lose health, you gain damage, and with each percent of damage you receive the ways moves and techniques impact you changes. You would think that having low percentage is always better, but you are more susceptible to combos and chain-grabs, and at higher percentages you are more likely to be blasted off the stage.
All around Brawl has many more layers of depth than Tekken does. You can't deny that regardless of how you feel about either game.
Edited to avoid wave of nonsense