I wouldnt mind hearing a good answer to this, too.. I've found guides to how to raise stats, but even after I spend aw hole match doing nothing but strikes, or grapples, or whatever it says to do for a stat -- my stats will go up by like 1, or even a fraction of that. My STR went up by less than half a bar once.
There is no fastest way, there is only one way. Play matches, don't squash your opponent and win in under a minute and generally do the following things.
Durability - Winning the Match, receiving Damage, Being Busted open , Finisher Kick outs, Strong Grapples. Tips: Take a lot of damage, i've found the WWE and WHC paths the best to get this stat, Using Single with Manager matches is most likely your best bet, to increase your chances of winning, and to note I always seem to get a fair amount if i don't take damage and Do alot of strong Grapples.
Strength - the only Thing i've found that Definately adds to this is strikes, I also think hitting finisher and Sigs add to this. Tips: Defend the IC/US title in a cage match, and do nothing but strike attacks for the first minute of the match, I USED nothing but strikes and one ONE finisher, and it half filled my 86 strength bar everything else stayed still, I've heard some people claim UCM, in my experience UCMs add to Stamina and Tech.
Speed - Running Moves, Top Rope, Dives, Quick Grapples Tips: Ladder and TLC matches, be a cruiserweight for a while, run jump fly, I always do an off the ladder in the ring, to table outside dive, and i throw in the mindless destruction of the announce tables via the special elbow, Using your quick Grapples will also Boost this.
Submission - Submissions, working limbs, Ground Grapples Tips: Just apply SS I found 10-15 = 1 and a half bars, and Try and get them completly red from submissions and other Ground moves.
Technical - Reversals, and Technical/Ground Moves, UCM, Tips: Best place for this is the WWE and WHC paths, just try and get as many reverses as possible, even if you lose you'll still get a fare amount of Stat, Strong Grapples
Stamina - Kick outs, Bleeding, winning with little damage Running, Stamina System, UCM Tips: Turn Stamina on, and have Longer matches let it run out, I've found holding on SS submissions for longer also boosts it, as well as Drawing out UCMs.
Charisma - taunting, Aerial moves, Fan Favourite Taunt Tips: I'd suggest using Aerial moves, Ladder Dives, outside Dives, taunt a lot, Cruiserweight grapples might also help, and the hotspots around ringside which allow you to interact with the fans.
Hardcore - Weapon Strikes, Weapon Grapples and Out of ring moves ... Tips: this is simple, choose a match, I prefer ECW extreme rulez, then destroy the other guy with weapons - if you have object grapples use that, just vary alot and this should soar, I'm 90% certain Finishers and UCM done outside of the ring, Set tables and Barb Wired bats on fire, Pretty much be hardcore...
Here's what I'm doing I'm using all the medals you win during the matches. Meaning I made a list of how to get all the medals and I've been doing each requirement to achive them. I'm using a diva and I'm on my fourth match and I'm at a 63 overall. It drags out the match length and you always get 5 stars (for a diva CAW). I seem to go up pretty nicely in stats after a match. A little friendly warning though it gets boring as hell dragging a match with Candice out for an hour but it works for me. Hope this helps a little bit.