There are ways to change rules. The best way to get rid of a rule you don't like is to go into a region where they don't use that rule, and then come back again. I think Timber uses different rules (and not the Random rule).

Basically, what you should do is go from Dollet to Timber. Initiate a card game with someone. When they say the whole long speech about "You know different rules, let's combine the two...Do you want to play?" say no. Repeat until he just asks "Do you want to play?". You want to do this, otherwise you run the risk of spreading Random everywhere!

Once you've played a game with Timber rules, run back to Dollet. Then, play a game combining the two rules (you may lose your cards if Random is in use, but you can always win them back later when you've abolished the rule). Afterwards, one of three things might happen: nothing, a rule may spread, or a rule may be abolished. If the rule is not abolished, run back to Timber and repeat the process until it's gone.

This is quite a mission - made much easier once you have the Ragnarok, but still, what can one do? Alternatively, you can just beat the guy with the Random rule in play. Although you can be raw dealt, you can always come back. Worst case situation, just save your game before you play, and if you lose an important card, just quite and reload (especially important when you want to win the Laguna card in the Space Station later - my word!).