Well I'm not sure what you mean by your enemy, but you deserve a 'mon either way!
Take Special the Turtwig. Turtwig always remembers the first move of each type it learned, which is special as its the first move of that type it learned. It may not learn any other move of that type. So Tackle will be your first Normal-type move and Withdraw your first Water-type move. You may forget them in favor of other types, but you may not learn any other Normal or Water-type moves.
However, when Turtwig faces an opponent that uses any of these moves, it must forget the move that it has used. The move isn't special anymore. Then it is allowed to learn a new move of that type, but once it has learned a new move the same restriction applies. It may never relearn the first move if this happens.
Curse counts as a Ghost-type move.
Good luck and have fun. This should be fun yet somewhat challenging. You are restricted in your moves, so you must use creativity to beat your opponents, however, you're also able to somewhat influence it if you want to hunt for for example a Bidoof to forget Tackle for a better Normal-type move later in the game.
You may use Tackle until you get a new attacking move, even if you found something that also used it. However, as soon as you get a new move, you may not use Tackle again. This doesn't count if you get a new Pokemon before you learn another move, then you'll just have to Exp. Share / Switch train it!
