go in the lake enterance and he or she should be there.
To get Lickitung in Pokemon Pearl you need the National Pokedex which you get for seeing every Pokemon in the Sinnoh Pokdex. After getting the National Pokedex talk to your rival's sister in Sandgem Town until she says Lickitung have started appearing in Acuity Lackfront. Go to Acuity Lakefront and a Lickitung should eventually appear.
Go to the place where you can walk with your Pokemon and it's in one of the places. Town: Hearthome You can also get it at the Acuity Lakefront, Route 229, and at Turnback Cave
After the player defeats Gym Leader Candace at the Snowpoint City Gym, the player should return to Lake Acuity. There they will discover that their rival has lost to Commander Jupiter.
Your rival.
After helping your rival at Lake Acuity, your next step is to complete the gym in Snowpoint City. If you've already completed the gym and have the Icicle Badge, your next step is to make it to Veilstone City to deal with Team Galactic's HQ.
It matters what starter you choose
You only have one rival (or do you mean the second time you battle your rival?)
Rival
he gives you $6400!
anything you want
Go to the library in Canalave city after you fight your rival their and talk to prof. rowan, after the story go lake verity then to lake Acuity near Snowpoint City
you talk 2 your rival and she/he gives you one