Here's some that I played during my Bz playing career...

(Most of these aren't mine)
Scouts vs. Bombers
Game: Deathmatch
Recommended Maps: Armageddon, Battle Arena, Crown, Coliseum
Razors, BDog Razors, and Flankers are on one team and Thunderbolts, BDog Thunderbolts, and Grendels on the other... Team Deathmatch style.
Turrets vs. Walkers
Game: Deathmatch
Recommended Map: Leap of Faith
Badgers, BDog Badgers, PAKs, and Landers are on one team and Sasquatches, Sasquatch AGs, and Golems are on the other... Team Deathmatch style.
NSDF vs. CCA
Spork has already listed this but if it's a Deathmatch, try this...
Map: Singularity
-Team Composition for both teams-
- 1 Tank, Light Tank, or Scout
- 1 Rocket Tank or Bomber
- 1 Turret
- 1 Walker
Czars vs. Grizzlies
This is more of an extreme form of NSDF vs. CCA.
Flankers vs. Razors
Yet again... an extreme form of NSDF vs. CCA.
Landers Only
Game: Deathmatch
Recommended Maps: Leap of Faith, Coliseum
This becomes very funny, very quick... Trust me.
Stock Bombers Only
We've seen these games plenty... Try doing Armageddon or Crown for once.
BDog Grizzlies vs. Stealth Grizzlies
Game: Deathmatch
Recommended Maps: Coliseum was the default back around 2002 but since we now have Battle Arena and Io, we now can choose a different map so often.
Stock SP-Stabber Equipped Grizzlies (BDog Grizzly) are on one team and Stock MAG Cannon Equipped Grizzlies (Stealth Tank) are on the other. This is quite interesting once the battles start... Though, kinda hard to tell Grizzlies apart...
Walkers Only
Game: Deathmatch
Recommended Map: Leap of Faith
Walker-only Free-for-All.
Attack and Defense
Game: Strategy
Players: 1 vs. 2, 2 vs. 2, 1 vs. 3
Recommended Maps: Blast Chamber is the best but any map with a relatively level and/or flat center, or with a location to defend, will do.
Defense team, usually the outnumbered one, gets a couple of minutes (set by agreement) to setup to hold the area. If they have no buildings or units (pilots and soldiers don't count) in the area, the attackers win. If they fail to take the area, defender wins.
Defender needs to either know how to construct a fortress of pain or be very good (
Pro Stratters.)