Name of the Digimon Game?

I remember a digimon game that I believe was for a handheld device or ps1 (gba,gbc,nds). It involved a hightech city and you picked 1 of 3 "clans". You went into dungeons with a vehicle thing (kind of looks like a star wars walker). It only had a certain amount of fuel and could break blocks and stuff if you upgraded it. You collected digimon, you could visit different buildings within the city (you could only walk around in the buildings, not the streets). I just can't remember the name of the game. combat was 3v3. You found lots of digimon in the dungeons and there's a boss at the end of each.