Building a helpful character [3.5]

[Epsilon Rose]

Hey, my gaming club is going to be putting on a one-shot to give new players a taste of D&D and I've been asked to play as well in order to help them and I was wondering if anyone could suggest some builds or character options that I could use to basically make sure they can get through things and have some fun.
The one shot's going to be a generic dungeon crawl, possibly with a dragon at the end. We'll be playing as level 5s with all books open and the dm has suggested I play a tier 1 character since it might be a bit to complicated for the newer players and a wizard can do a good job of smoothing things out but I'd rather not play an actual wizard and I'm currently thinking of going archivist.

I'd greatly prefer something oddball and unusual even if it drops me a tier.
Thank you.

[Sacrieur]

Anything tier 1 or 2. Wizard, Artificer, Cleric, Factotum, etc...

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I would suggest a buffing Cleric, since that's a support role.

[Flickerdart]

For a helper character? Bard! Crank up your Inspire Courage or Dragonfire Inspiration and lean back. You get 2nd level spells at 5th, so a well-placed Glitterdust to go with that 4d6 fire damage will go a long way.

[Hiro Protagonest]

I say cleric of war or a war deity, they get decent combat abilities while retaining full spellcasting.

[true_shinken]

I'd just play a t1 class I hadn't played in a long time.

[Jack Zander]

I'd greatly prefer something oddball and unusual even if it drops me a tier.

Dwrven Cleric boost constitution and AC to the max, extend spell shield other the entire party and keep yourself well healed every turn. If something tries to cast an AoE damage spell, silence or counterspell. You might not be able to several damages at once even if everyone saves for half.

What's nice is you are still pretty much a standard cleric. Just keep your health high and the protection you'll be giving the new players should make the experience more enjoyable for them.