How viable would a team be if all pokemon were part dragon?

With three weaknesses in
Dragon: ignorable, presuming your dragons are better/faster
Ice: No ice priority, no one uses ice pokemon, only ice moves, and flamethrower kills nicely if it comes to it.
Fairy: biggest threat, but iron head Garchomp can still kill right? Or Dragalge with poison STAB?

The real threat to a dragon is speed vs dragon/ice/fairy.

Now to their stats.
Most dragons are bulky, and most are mixed types with great movepools and have good speed, with Noivern and Garchomp being your saviours.

Goodra can even be a bulky special wall to a degree, Dragonite w/ multiscale is another. And they all have four resistances in basic types which can be quite useful when combined with their other type.

Kingdra - water
Mega Ampharos - electric
Mega Charizard - fire
Hydreigon - dark
Garchomp - ground
and others.

So is it viable to create a dragon team as the weakness to such may be countered and covered by other dragons?