On Martian Manhunter

Slim

Shell gas stations in Canada ran a promotion resulting in the release of eight characters, including Martian Manhunter, on slim blister cards, without mini-comic, in 1985. Consumers were afforded the opportunity to purchase one of eight specially carded Super Powers action figures with a fill-up of 25 liters (litres) or more for $1.99 (CAN). Eight figures were released on slim cards, including: Superman, Batman, Robin, Wonder Woman, Green Lantern, Red Tornado, Martian Manhunter, Firestorm. 

Overall the 1st series characters tend to show up carded on the collector's market in higher quantities than the 2nd series characters, however assembling a complete set is fairly easy. Larger quantities of the more well known 1st series characters were likely produced, explaining their higher abundance. Collectors have documented finding these slim cards at closeout retail stores like Kay Bee Toys (Playland) and Tuesday Morning. It is widely believed Kenner created this narrow profile to easily fit store checkout lanes, stocking stuffers, or specialized international promotional displays.