Well, I’m not saying B3 is deep because of the combos and the skill required to execute them. I’m saying B3 is deep because the mix-ups are deep and innovative, and that every character is capable of them. I tend to avoid character strategies when it comes to depth (things like zoning, locking, etc) just because they’re more of icing to the cake. But they’re there. You can’t expect to zone like Piccolo with Teen Gohan or Goku. You can’t expect to use Bardock’s incredible close range fighting with Hercule.
The game offers options for the offence and the defence, its just that the offence is usually at an advantage because they either have frame advantage with attacks (while the defender blocks to gain ki but loses frame advantage, or dodges and loses ki in attempt to gain frame advantage), and if the offence is charging an attack, it could be a nullifying attack (which means that the offence can take 1 hit without getting stunned), which puts them in both in an offencive and defencive position.
The defence can defeat the offence, its just a bit more difficult, one reason that they only have a slight clue as to what chain their opponent is using. Take Goku’s ->PKK for instance. If the defence does guess that Goku goes for ->PKK, they can immediately interrupt him right before the K (if they dodge the ->P) and go off into a combo of their own. However, Goku has his ->PP<-PP, which is a much faster chain, has decent tracking, with a chargable <-P. There’s a good mix-up right there.
Assume Goku manages to use ->PKK without getting interrupted. He charges the last K. While charging, he’s invulnerable to one physical attack. On top of all the many options he has, the defence can fight back. They can use grabs, try to catch Goku with a fast chain, use a power move of their own to activate the burst zone, back dash, or try to keep defending, since Goku can’t combo off of his last K or his throw. They can try to backdash upwards, and as soon as they get hit when they start leaving the ground, they’re already in a very good position to evade a juggle. They could anticipate that Goku will use the fully charged K and attempt to sidestep. I’d list firing a ki blast as a strategy for the defence, but Videl, Hercule and Uub can’t do it, so its not for everyone.
But the options I listed otherwise for the defence can be done with each and every single character in the game. And I think that’s enough for B3 to be warranted as a decently deep fighting game. I’m not saying B3 is deeper than any of the mainstream tournament fighters (3S, MvC2, etc), but it’s definitely got enough for its own.
As for SDBZ, I give it a bit of a break since its a first attempt. Most fighting games in general don’t get it the first try. Think of SC, Tekken, VF, SF and most fighting games in general. Some do, but the majority don’t. For now, I’m just trying to get the most out of SDBZ as possible, and I’m working on a combo/mechanics guide for it. I don’t know when I’ll be done, but I’m already more than halfway through.