You may suceed in the game but then people will get bored of you, and will figure out a way to counter that move. I think we need a variety of moves.

all you need is a move to cover every eventuality. just study the person's moves so you know what they will do. pretty much all judo starters fall into one of three categories:

Straight grab: completely symmetrical move
Twisted grab: same as first, but favoring one side
Kick grab: same as second, but following with a leg

knowing that, I have a move to counter each of them. the only tricky part is guessing what they will use.