Shambling along in untidy groups, their eyes bloodshot and voices hoarse after long months of trailing round London's innumerable Edinburgh previews, the comedy battalions make their ragged way north of the border. For the next three and a half weeks, they will be constantly harried by the fascist running-dogs of the media: braying TV researchers, drunk on delusions of their own significance, maudlin journalists, mumbling brokenly into their lager that they are people, too. But these depredations must be born nobly and with forbearance.

Simon Munnery's Alan Parker - Urban Warrior (Pleasance) has a particularly glossy look about him this year. Whole belief systems have risen and crumbled since Parker's patent brand of self-validatory sedition first saw the light of day, but for this particular streetwise revolutionary the time does finally seem to be now. And if he is - as last week's London Shouting TV pilot suggested - about to get to grips with a mass audience via the degenerate medium of late-night television, then all the honing and the buffing will have been worthwhile. Alan's heroic struggle to reconcile the personal with the political is not without its casualties though, and he is going to have to do something about his hostility towards the Dutch. Now that the world stage beckons, lines like "What are windmills really but swastikas put to a practical use?" could have serious international repercussions.

Those in search of radical, risk-taking entertainment can also turn - albeit with some surprise - to Annabel Giles (Pleasance). With so many people falling over themselves to swap the life-affirming hurly-burly of Edinburgh for the hermetic swank of TV-land, it is heartening to meet someone coming back the other way. But that is not all there is to it. Giles's second one-woman show underpins its deconstruction of celebrity with a healthy measure of conceptual audacity, and for all her hyperactive self-deprecation, there are more moments of authentic spontaneity in this very amusing 50 minutes than in three months of Eddie Izzard in the West End.

Not many up-and-coming stand-ups can boast the reassurance of a Bafta on their mantelpiece. Having already written for Steve Coogan and Mrs Merton, Dave Gorman (Pleasance) shows every sign of becoming a star in his own right. His dry wit is sometimes tinged with cruelty ("Why did we collect milk-bottle tops for the blind? There's no way on earth they thought that was real money") but he has a great knack for rendering a complex thought process in seductively simple form (and vice versa, when the occasion demands). Half-way through his act, Gorman swaps cardigans and does a character: another stand-up whose material is uncannily similar to his own. "He's the white middle-class comedian type. There's lots of them around - I think it's quite closely observed."

The appearance of suavely pin-striped Sean Lock (Pleasance) is a far cry from the scruffy comedic stereotype. Barely recognisable as the tragic individual who supported Newman and Baddiel at Wembley Arena, Lock is now a ferociously accomplished performer who blends moral obfuscation with aesthetic absolutism to potent effect ("The only good reason to kill an animal," he maintains devilishly, "is to make a nice display"). Some of his best routines arrive at a similar destination to Harry Hill's, but via a different route.

There is a strange moment in the middle of Lock's set when he tries to engage a member of the audience in some traditionally one-sided banter, and the supposedly defenceless punter responds with snippets of Father Ted dialogue. The hidden message concealed within this exchange seems to be: "Given the heights of sophistication scaled by British TV light entertainment over the last couple of years, where next for the live body comedic?"

One answer that has been put forward to this question involves - and those of a nervous disposition are advised to cover their eyes at this point - the word "sketches". The big problem with sketch comedy is that it tends to be a means for resting actors to show why script-writing is not an option for them. Happily, both the commendably grotesque League of Gentlemen (Pleasance) and the well-integrated Armstrong & Miller (Pleasance) manage to evade this categorisation. The former by their eloquent testimony to the effects of sexual frustration on creativity, the latter by being engaging and energetic performers with considerable insight into the ways of the fairground.

The Bastard Son of Tommy Cooper (Pleasance) is a one-man freak show who sticks skewers through his tongue, lifts heavy objects with his penis and swallows not one but two swords at the same time. But the real shock of the festival so far is Californian ventriloquist David Strassman (Spiegeltent). There is nothing particularly revolutionary about Strassman's puppet friends - psychotic Chuck Wood, nauseating Ted E Bear and failing-to-elicit-any- form-of-emotional-response Beaky the Beaver - except that through the wonder of discarded Nasa technology, and only when the mood takes them, they can actually move about without human assistance.

The short-term consequence of this epoch-making development is the most hilarious animatronic baby-dinosaur karaoke routine ever seen on British soil. But in years to come, when historians come to look back on the death of the noble art of ventriloquism, there will be no denying that David Strassman had a hand in it.