'Tis the season (I always think to myself around this time of year) to be jolly. 'Tis the season for Christmas shows, mounted by artistes whom we'd be inclined to label "novelty" acts, if it weren't for the fact that Gary Glitter has been doing the same concert, for audiences of wildly varying numbers, for more than 20 years.

This year, he's performing for crowds of 12,400 people - or rather, they're performing to him. At the London Arena last weekend, Glitter's 56-year- old voice wasn't up to the job of shouting "Oh yeah" 400 times over the racket of two pounding drum kits, so he relied on the audience, wrapped in Bacofoil and tinsel, to do it for him. It was uncomfortably forced and tawdry. Call-and-response clap-alongs are as essential an ingredient of Christmas shows as turkey is of Christmas dinners, but no one wants to swallow a whole turkey without any of the trimmings. Glitter's vaunted showmanship boiled down to his holding up his fists for a minute at a time while the crowd chanted "Lea-der". And I expect he went through this routine simply because it allowed him time to get his breath back, given the effort of carrying that permed dog on his head.

This being a time for giving, however, I should acknowledge that he played some surprisingly respectable tracks from next year's album, Lost on Life Street. These had actual melodies, instead of just a title and a drumbeat, and Glitter was revitalised as he sang them. It's ironic, considering that he exists to play the oldies, that his best songs were the ones that the audience didn't know off by heart.

Bjorn Again have updated their act, too. "It's fine to play this nice music, but I vont to be rock god," complained "Benny", and the original Australian Abba tribute band - indeed, the original tribute band, period - belted out Supergrass's "Alright", and Oasis's "Roll With It", complete with a Mancunian "Thank you very mooch" at the end.

Maybe they have been driven mad by eight years of putting on Swedish accents and singing "Dancing Queen", or maybe they were just trying to stop themselves going stale. It was a commendable gesture, but on the evidence of their show at the Shepherd's Bush Empire, an unnecessary one. If there has been any drop in quality since Bjorn Again first sewed sequins on their flares in 1989, I didn't notice it, and I must have been much more censorious than the average audience member, in that I wasn't a) a student, b) an Abba fan, or c) drunk. A kimono-clad "Agnetha" and "Frida" had mastered the choral harmonies, as well as the patented Abba choreography (face each other, face away from each other, stand shoulder to shoulder, repeat). "Benny" and "Bjorn", on keyboard and guitar, could handle every one of their models' baroque-disco flourishes, and switched to acoustic guitars for "Fernando". The audience sang along with joyous gusto, waving sparklers as they did so. Cigarette lighters, it seems, are for wimps and heavy-metal fans.

This pacey, funny, enthusiastic show was as merry as you'll get this Christmas. My only complaint is that the brunette was better-looking than the blonde, which isn't how I remember Abba at all.

The pretenders to the tribute-band throne are No Way Sis, who have earned themselves a record deal with EMI purely by copying Oasis. This may not seem so special in the wake of Northern Uproar and the Real People, but the difference is that No Way Sis ("the new Bootleg Beatles", as they must be called) own up to it. They cover Oasis songs. They dress up as Oasis. They've released a single of the New Seekers' "I'd Like to Teach the World to Sing", in the style of Oasis. And all this while Oasis, unlike Abba, are still playing live at regular intervals themselves. This tells you all you need to know both about the Gallagher brothers' mind-boggling superstardom - and about record companies' commitment to searching out fresh, risk-taking talent. On Thursday, five Glaswegians who should have been amusing the punters in the back room of a Partick pub were at the Shepherd's Bush Empire, charging pounds 10.50 a ticket.

As anyone who has experienced a Oasis "show" in the last couple of years can attest, it shouldn't require an inordinate amount of musical virtuosity or rigorous rehearsal to pull off a Stars in Their Eyes version. While it would be a gifted group indeed who could convince as, say, Half-Cockered or Beck to Life, Oasis are eminently imitable. Or so I thought, before I saw the impersonators.

"Liam", gasping for breath mid-word, failed to keep to his inspiration's phrasing, and to keep his attempted Mancunian accent from driving North. After the first song, he was losing his voice. "Noel", sadly, wasn't losing his. His guitar-playing was worse: scratchy and droning, when it should have been swirling and liquid. The drummer, however, was very much like Oasis's drummer - Tony McCarroll, the one they sacked. And Bjorn Again's "Roll With It" was closer to the real thing.

As Oasis's ability to complete a tour of America seems to be doubtful, I was going to suggest that they send their doppelgangers in their place. However, having seen No Way Sis, and heard the B-sides of their single ... no way, Jose. But let's remember, once again, that it's Christmas. The ersatz Liam's tambourine playing was very nimble indeed.

Gary Glitter: Manchester Nynex Arena, 0161 930 8000, tonight. Bjorn Again: Ilford Island, 0181 514 4400, Sat.