Our current campaign is fun, but our DM does not make challenging battles at all. I'm retiring a rogue who does a ton of damage but it's way overkill.  I want a build that focuses more on fun In and out of combat utility/abilities.  We already have an artificer, sorcerer and ranger.  We don't need a full healer, and don't have much need of crowd control.

I'm open to wacky multiclasses.  Staring at level 12.

You could try playing a monk. Monks get a ton of class features, and they basically outrun bullets with how fast they get at higher levels. Also, you get to make as many anime references as you can stand. I haven't played one yet, so I can't speak from experience here, but I've heard great things about them, and they seem promising.

I am currently in the process of making a Bard/Monk.

Lots of skills, a little magic, and when the poop hits the fan I can kill them with a sharp tongue and my left thumb.

Glamour Bard/Celestial Warlock with Unicorn patron.

You could try using Sidekick rules from Tasha's. 

Alternatively Alchemist Artificer does good support/ some healing while not focusing a ton on damage. 

Or you could go Redemption Paladin, where finding ways to avoid doing damage directly is like a core part of the oath.

Quote from ShawnBrynelson >>

Our current campaign is fun, but our DM does not make challenging battles at all. I'm retiring a rogue who does a ton of damage but it's way overkill.  I want a build that focuses more on fun In and out of combat utility/abilities.  We already have an artificer, sorcerer and ranger.  We don't need a full healer, and don't have much need of crowd control.

I'm open to wacky multiclasses.  Staring at level 12.

 

You could go with a Dr Doolitte-esque druid or druid/Pact of the Chain multiclass who mainly focuses on summoning creatures -- not for combat purposes, just because they like to have a traveling menagerie around them

Bardbarian 

Gnome or Hafling at 8th level Bard (College of Eloquence) and 4th level Barbarian (Wild Magic) 

Select spells that focus on charm, trickery, and to avoid violent confrontations as much as possible (no Vicious Mockery).  In combat, the character tries convince the party members to resolve any disputes via non-violent means. They cast spells in an attempt to bring encounters to peaceful and hopefully equitable solution. 

If, however, something causes the character to Rage....the character hunches over and pants heavily.  Hair grows across their body, nostrils flair, and the character gradually adopts a more feral appearance. Wild Magic erupts from the character as they pull out two jagged scimitars and leaps with a blood lust for destruction. 

Grappling luchador monk/barb multiclass? Go full strength based and really embrace the pro wrestler WWE aesthetic.

Illusion wizard!  They don't specialize in damage or control, they mostly just specialize in shenanigans.  Your creativity is the limit for what you can do.  You and your DM might need to review illusion spells or watch a video like this one to really make sure you know what you can and can't do with these spells.  I played a changeling illusionist in a one shot recently and I had soooooooo much fun. 

Are the battles unchallenging because your DM is a very poor war-game tactician, or are they unchallenging because they are failing to bring enough CR to the fight? 

Uh, idk really know anything much about dnd, and I still haven't fleshed this out yet like what class and stuff, but I had an idea for probably a Variant Human or Half-elf that is insane, wears a plague doctor mask and thinks that he's a Kenku.