Given the requirement of a "strong, colorless energy attacker", another Poké (non-EX of course) that comes to mind is Simisear (Plasma Storm). As you know, Reshiram is the best R Poké with a colorless energy attack, but the KK deck players can easily "play around" Reshiram and attack your more valuable resources. Simisear, IMHO, just may not inflict enough damage to really counter a KK deck.
So, with that being said, should you do consider adding a few R energy, then you can open your deck to more R Poké possibilities to effectively counter KK decks. For example, you have a variety of Poké you can review, select and playtest. Following are some basic and stage 1 R, non-EX Poké (I choose to omit stage 2 R Poké just to minimize disruption to your current deck when you incorporate any new R Poké) you might find interesting enough to consider:
- Arcanine (Next Destinies #13)
- Camerupt (Boundaries Crossed) (Plasma Storm)
- Flareon (Plasma Freeze)
- Heatmor (Dark Explorers)
- Magmortar (Dragons Exalted)
- Moltres (Next Destinies)
- Ninetales (Dragons Exalted)
- Volcarona (Dark Explorers)
They all have different capabilities and attributes; and hopefully, one will best suit your particular needs and playing style. By the way, do consider adding a Team Plasma Badge (or 2, especially if you are running Deoxys in your deck).
I hope you find these comments helpful.
