I've tried it with Furret, with Boost, with lone helpers like Spinda, and they've all lead me to the same conclusion; Garchomp needs energy acceleration to keep up with decks like Magmortar, Blissey, and Gallade. Not being able to abuse DRE and still use it's poke-body hurts Garchomp a lot. Garchomp has the ability to do really good damage really quickly, making it a card that if given any decent way to accelerate energy, it could do very well. But right now, it is missing that one aspect that keeps it from performing at the same level as the big decks.
Furret doesn't work because after you Baton Pass, you leave the opponent open to attack Garchomp once before Garchomp can even attack.
Raichu doesn't work because it doesn't help setup Garchomp and it takes away resources to setup a Raichu before you can setup a Garchomp. Also, it limits your energy types.
Spinda is great and I love the card. With strength charm and plus power, Spinda is AMAZING. I've T1'd someone with Spinda. I've KO'd a blissey with 70 damage on it with Spinda. Spinda is a overall great card. But it doesn't help setup Garchomp and shouldn't be any kind of starter.
Smeargle helps get energy, but it doesn't help setup. And even when you do get a garchomp up, you can still only attach one energy per turn. Smeargle leaves your hand open to Wager shuffling all that energy back in and wasting your attack/s.
Boost energy is great with Garchomp. I actually T1'd someone (going second) with Gible, rare candy, Garchomp, and top decking a boost energy this past Sunday at a City Championship. But 70 damage isn't that great. It two-hit KO's most in the format and that's not that great because Boost energy gets discarded and you have no energy on Garchomp afterwards. Also, Boost energy provides fast damage but the real idea of the deck is to abuse Garchomp's poke-body leaving you in many situations where you have to Boost to deal damage but you need the 110 damage to KO the threat.