Random counter types (like Char and the Lightning marker Doc mentioned) can be anything you want as long as they are not confused with damage counters.
Char, in essence, is identical to Burn, except Char counters do not go away when the Charred one is sent to the Bench; getting KOed, devolving, and evolving are the only ways to get rid of a Char counter.
Here is an actual scan of the card:
Like armaldoEX said before, this Quilava is the only pokémon that has the ability to use Char counters.
Other Japanese-only cards that utilize strange markers include:
-> Grimer, "Grimer counters"; For one Grass energy, if the Defending Pokémon doesn't have a Grimer counter on it, it gets one. Pokémon with Grimer counters on them can't retreat.
-> Marowak, "bone counters"; For one of any Energy, player puts a bone counter on Marowak. There is no limit to the number of bone counters a Marowak can have. Its second attack causes 50 damage for FFC, with paralysis on a heads flip. The catch is you must remove a bone counter from Marowak every time you use the second attack. If you can't, you can't use the move.
-> Greedy Snorlax, "food counters"; For one of any Energy, player puts a food counter on Greedy Snorlax. It can only be used if Greedy Snorlax has less than two food counters on it. Its second attack costs three of any Energy and has 20 base damage; damage increases by 30 for each food counter you remove from Greedy Snorlax when you use the attack.