West Coast Avengers #10

In between p1 and the rest of the issue a lot of stuff happens (based on the Marvel Chronology Project).
The whole team, including Firebird and Thing, get involved in the grand finale of Secret Wars II in #9.
Thing has the last issues of his own series, #33-36. In #33 he learns that the other UCWF wrestlers have been enhanced by the Power Broker and Dr Karl Malus. In #35 his friend Sharon Ventura undergoes the process and becomes the new Ms Marvel, but she avoids getting the addictive drug that PB used to control the others. But in #36 Thing's body mutates (nothing to do with PB) and he flees rather than face Sharon and She-Hulk or anybody else. Which is what's happening in this issue.
Meanwhile the core team are called in with Thor by Captain America to help the Eternals deal with the Deviant Ghaur who's stolen the power of the Dreaming Celestial (buried beneath California's Diablo Mountains). And then Iron Man has his #205-208 where he fights AIM while starting a new company and building a space station. Hawkeye and Mockingbird guest in #206 with WCA's ongoing prisoner Goliath.

Wasp goes into more detail about the supposed limit of 6 members per team. Their antagonistic government liaison Henry Peter Gyrich imposed a limit of 7 members on the (East Coast) Avengers team as a condition of restoring their priority privileges in Av#181. Plus the government got to choose the members. But this restriction was actually eased in #192 when Gyrich's rule was forcibly relaxed. It was really Captain America who reduced the normal team size to 6 in #211.
Then in #258 the Avengers lost their security clearance after Vision tried to take over the world in #253-254. But Jan Van Dyne puts a positive spin on that by saying that if they're no longer an arm of the government then their rules don't apply, so the teams can be any size.

But Hawkeye should actually be kicking himself over this because he should have known that the government restriction was only to 7 members, so he could have inducted both Thing *and* Firebird even without the change of status of the Avengers.

She-Hulk came from New York to LA in Thing #36 because of news reports of Ben being involved in property destruction (presumably during the fighting amongst UCWF wrestlers in #35). Since Secret Wars #9 and its epilogue Av#266, she and the rest of the Fantastic Four have been caught between Annihilus and Blastaar in the Negative Zone in FF#289-290 and been trapped in a fake time-warp in FF#291-292 where Nick Fury thinks he can assassinate Hitler. Then in Marvel Fanfare #37 Reed Richards tried to use Hermione Granger's time-travel method of getting more things done in a day.
After SWII#9 and Av#266 Wasp led the Avengers to intercede in a dispute between Magneto and White Queen over the New Mutants in NM#40, and then another dispute between Kang and Immortus in Av#267-269. In #270 Moonstone incited public feelings against Sub-Mariner as the opening salvo in an upcoming conflict with a new Masters of Evil.

Headlok is a totally new villain. I don't think he is ever given an origin or a reason for what he does.
Griffin was a minor hood who was surgically transformed into a super-villain by the Secret Empire in Amazing Adventures (Beast) #15. By the time he fought Beast with Spider-Man in Marvel Team-Up #38 he had mutated into a more bestial form and become more beast than man in his mind too. He seemed more rational in a group of villains in Champions #7-10, but went solo again against Wonder Man and SM in MTU#78.

The WCA will next be seen in Hulk #320-323 where they will help capture him and reunite him with Bruce Banner. Then Hawkeye and Iron Man attend Iron Fist's funeral in Power Man & IF #125, the final issue of the series, while Henry Pym has a more active scientist-role. (But IF's not really dead, it's an alien imposter.) The IM wanders off to his Annual #8 to team up with X-Factor, while Clint & Bobbi go to New York to testify against Crossfire and team up with Captain America against Armadillo and the Death-Throws in CA#316-317.
Wasp and the Avengers are also in Hu#320-323 and play a larger role in PM&IF#125.
She-Hulk is also in the Hulk issues. The FF see her off in Hu#321. Mr Fantastic does science with Pym in PM&IF#125 before he attends the funeral with wife Sue. And the couple then cameo in IM An#8.

Thing shows up next in FF#296 on Monster Island with Mole Man but the FF persuade him to come back with them. His mutation appears to have abated a lot, but it'll get worse in FF#310.
Meanwhile Ms Marvel goes after Power Broker and Malus. But in CA#330-331 she's been captured (and we later understand raped). After Cap rescues her he brings her to New York where she meets Thing again and joins the FF in FF#306. But in #310 when cosmic rays further mutate Ben they also turn Sharon Ventura into She-Thing whose body then resembles Thing's earliest lump form.

Firebird will return in #17-25 as La Espirita where she will help rescue the team who have been lost in time. And along the way she will discover the story of Carlotta Valdez who she saw in her vision in #8.

Headlok's next app will be Alpha Flight #93-94 guest-starring the FF where he'll turn some members of both teams against the others.
Griffin will be seen next in CA#340 where Steve Rogers as The Captain stops him and others breaking out of the Vault. This is part of Iron Man's Armour Wars.