Dropping the 2-2 Slowking for a 2-2 Gliscor, you're actually using the same deck I'm running.
My main issue has always been getting Vileplume up fast enough to ensure the lock is in place. Once it's up, the deck is solid. The other main issue I've run into, is the inability to get back Special Energies
As of late, people at my local league have been running Lost Remover like crazy, which would absolutely ruin the speed factor of this deck.
2-2 Gliscor
3-3 Beartic
1-1 Dodrio
2-2 Zoroark
3-2-2 Vileplume
2 Zekrom
Everyone there benefits from a rainbow/DCE in some way, Lost Remover kills my version of this, if the lock isn't in place asap.
Gliscor is an excellent Stage 1 for this type of deck, simply because he has 1 retreat, and his first attack takes a special/fighting, to do 30 damage, and paralyze. His next attack (tack on a DCE), does 50 and poison. This means you 2 turn drop Zekrom with no chance of retreating for a revenge outrage, or if Zone appears, you can cost him a Zone. Downside to Gliscor is Yanmega absolutely destroys him.
EDIT: awesome addition would be energy to trade a drawn water for a dce.