Koal is a Black Hole CO who boasts increased offense on Roads, and also has a relatively inexpensive power Bar.
Day-to-day Effects: All of Koal's units gain 10% increased offense when fighting on Roads.
Power: Forced March -- All of Koal's Units gain +1 Movement, and 30% increased offense when fighting on Roads, 10% otherwise. All of Koal's units gain 10% increased defense.
Super: Trail of Woe -- All of Koal's Units gain +2 Movement, and 40% increased offense when fighting on Roads, 10% otherwise. All of Koal's units gain 10% increased defense.
Even though Koal has no penalties and some bonuses he is still bottom tier. The bonus attack on roads is usually of little use, since players still should avoid leaving units on road tiles due to the absence of terrain defense there.
Still, under some circumstances the attack bonus on roads can become useful. Especially if contested cities border on several road tiles. Together with a com tower and the road bonus Koal can then 2HK (kill with 2 hits) equal units (infantries vs infantries or tanks vs tanks).
Also Koal does fairly well with direct units since he gets a movement bonus of 1 or 2 during COP or SCOP. Also during SCOP the attack bonus on roads becomes significant.