Since Kiki uses a Normal Gem to activate HItmonlee's Unburden, you can simply get any Ghost-type Mon and swap it in against Hitmonlee and you will have completely countered her strategy with that mon. Sandygast is found on the beach. Drifloon is next to Shade's gym (on a windy day/night), Frillish in one of the eggs, Shuppet, Nincada if I remember is available too.
Emolga is also available to you, who is strong against Kiki. Growlithe, too.
You can fish up a Grimer and train it into Muk. With a MInimize move-set is a force to be reckoned with, too. (Muk is a little bit of a favourite of mine)
Nidoran M is there, too, in the arcade.
Dugtrio, Sandslash are also very good mons available to you in the cave under the gate.
The game really isn't that hard, especially the early game, you just need to not use mons that are weak towards whichever gym you're fighting - or get a little bit creative my friend!
Good luck :)!