You need to extract worldmap.txt from rpu.dat to your "data\data\" directory, then you can simply remove the level checks. For example:
// original
enc_27=Chance:80%,Special,Enc:KAGA1 AMBUSH Player, If(Global(399) < 66) And If(Player(Level) < 5)
// edit
enc_27=Chance:80%,Special,Enc:KAGA1...