Combo: Radiant Elemental + Mindblast Best case: Turn 4 Radiant Elemental + Shadow Reflection + Mindblast + Shadow Reflection*5 Watch for Warrior and Druid because they have armor gain, need extra Shadow Reflection(s) for lethal.
I came up with something very similar for Mech Hunter, but I think you don't want to run Micro Machine in that slot. I had Quick Shot instead and was liking that result. With 4 minions the Stitched Tracker will get you either the one you're looking for or another Stitched Tracker (so you can eventually find Metaltooth Leaper or Mechwarper, whichever you need) but you might have to cast multiple Trackers. I think it's better to guarantee you can get the Turn 3 Mechwarper army into Turn 4 Tracker+Leaper, or the Turn 3 Tracker into Turn 4 Mechwarper army. You cut the odds of each of those lines working in that time-frame from 100% to 75% by including a 4th minion.
The idea is to cycle through your whole deck with Power Word: Shield and then double the :minion's attack.
This list has minimal cycling pre-combo, but is able to go off with a single Guild Recruiter, ending the turn with a 30/30 and a 20/20 (or so, you run out of cards in your deck eventually). The optimal goldfish is a little faster than Mind Blast priest and the consistency should be higher since you have effectively 4 copies of Radiant Elemental. The downsides are that the board matters and that you have to wait for a minion to attack without charge. (So this is partially an anti-combo combo deck)
For the Mind Blast deck I think you want to load up on cycling a little more, but that's really just a point of fine-tuning and not that critical.
Other decks I think have good potential: Quest Rogue (probably running some 0-mana minions and possibly running Preparation or Counterfeit Coin for the 5-mana quest card) Token Druid (the ideal finisher is probably Mark of the Lotus)
As far as I'm aware, Mechwarper is the only thing that can really be considered a 1-card combo (with Shadow Reflections) and even filling the board on Turn 3 and killing on Turn 5 is reasonable (with two hero powers). Between Tracking, mulligans, and Stitched Tracker, this deck is a lot more consistent than it looks on paper. I think this is the best deck in the brawl format. My preferred list cuts the Micro Machine from the above post and replaces it with Quick Shot.
I think the main contender against attack-based aggro/combo decks are the token or swarm aggro decks. I think these are kind of a weak natural predator that can potentially race or contest the board. Some of these decks include cards like Consecration or Lightning Storm, so they can potentially clear a board of 3HP minions with a little help from their own aggro minions.
Finally, the pure combo decks like Mind Blast Priest are trying to ignore the board and kill the opponent. All that interferes with Mind Blast priest (to take one example) is armor gain and a few secrets, so except for teching in those strategies, it's a straight race. Mind Blast priest is therefore weak against aggro/combo but generally strong vs pure aggro (which is a little slower IMO). Consistency in terms of how quickly you can race is the key thing here.