The following list indicates whether various Dreamcast games released within the United States support VGA output without need of a boot disc. I've personally tested every game listed below by using the respective original, commercially-released GD-ROM for each (with bleem! disc as a likely exception to the GD-ROM rule).
YES indicates that a specific game supports VGA output without using a boot disc, while NO indicates that a specific game doesn't support VGA output without using a boot disc. COMING SOON indicates that I'll soon have the respective game in my possession for testing.
Some games may support VGA output through use of a boot disc. Since this workaround can come with performance issues, however, I currently lack the time to test games that extensively. As such, for now, I won't specify whether games support VGA output after using a boot disc, although this may change in the future.
102 Dalmatians: Puppies to the Rescue
YES
18 Wheeler: American Pro Trucker
YES
4 Wheel Thunder
YES
AeroWings
YES
Alien Front Online
YES
bleem! for Metal Gear Solid
YES
bleem! for Tekken 3
YES
Blue Stinger
YES
Caesars Palace 2000
YES
CAPCOM VS. SNK
YES
Centipede
YES
Championship Surfer
YES
Chicken Run
YES
ChuChu Rocket
YES
Coaster Works
YES
Crazy Taxi
YES
Dave Mirra Freestyle BMX
YES
Daytona USA
YES
Demolition Racer: No Exit
YES
Dynamite Cop
YES
ECW Hardcore Revolution
YES and NO*
* Boots into VGA mode. Plays audio. No video past SEGA logo.
ESPN International Track & Field
YES
Fighting Force 2
YES
Flag to Flag
YES
Illbleed
YES
Jeremy McGrath Supercross 2000
YES
Jet Grind Radio
YES
Mat Hoffman's Pro BMX
YES
MDK2
YES
Metropolis Street Racer
YES
Monaco Grand Prix
YES
NBA 2K
YES
NBA 2K1
YES
NBA 2K2
YES
NBA Showtime: NBA on NBC
NO
NCAA College Football 2K2
YES
NFL 2K
YES
NFL 2K1
YES
NFL 2K2
YES
NFL Blitz 2000
NO
NFL Quarterback Club 2000
YES
NFL Quarterback Club 2001
YES
NHL 2K
YES
NHL 2K2
YES
PenPen TriIcelon
YES
Phantasy Star Online Ver. 2
YES
Razor Freestyle Scooter
YES
Rippin' Riders
YES
Roadsters
NO
Sega Bass Fishing
YES
Sega GT
YES
Slave Zero
YES
SnoCross Championship Racing
NO
Soldier of Fortune
YES
SoulCalibur
YES
South Park: Chef's Luv Shack
NO
Spec Ops II: Omega Squad
YES
Speed Devils
YES
Spirit of Speed 1937
YES
Star Wars: Demolition
YES
Star Wars: Episode I: Racer
YES
Super Runabout
YES
Surf Rocket Racers
YES
Suzuki Alstare Extreme Racing
YES
Sydney 2000
NO
Tee Off
NO
Tennis 2K2
YES
Test Drive 6
YES
Test Drive V-Rally
YES
TNN Motorsports: Hardcore Heat
NO
Tokyo Xtreme Racer
YES
Tomb Raider Chronicles
YES
Tomb Raider: The Last Revelation
YES
Tony Hawk's Pro Skater
YES
Toy Commander
YES
TrickStyle
NO
Ultimate Fighting Championship
YES
Vanishing Point
YES
Virtua Athlete 2000
YES
Virtua Tennis
YES
Walt Disney World Quest Magical Racing Tour
YES
Wetrix+
YES
Wild Metal
YES
World Series Baseball 2K1
YES
World Series Baseball 2K2
YES
WWF Attitude
YES and NO*
* Boots into VGA mode. Plays audio. No video past SEGA logo.
Zombie Revenge
YES