Here are the number of Pokemon that you need to add to your ranch to level it up. For example to take your Ranch to Level 10 you need to add 80 Pokemon. The max number of Pokemon that will fit into the ranch is 1,000.

2 - add 7 Pokemon
3 - add 10 Pokemon
4 - add 15 Pokemon
5 - add 20 Pokemon
6 - add 30 Pokemon
7 - add 40 Pokemon
8 - add 50 Pokemon
9 - add 60 Pokemon
10 - add 80 Pokemon
11 - add 100 Pokemon
12 - add 120 Pokemon
13 - add 150 Pokemon
14 - add 200 Pokemon
15 - add 250 Pokemon
16 - add 300 Pokemon
17 - add 350 Pokemon
18 - add 400 Pokemon
19 - add 450 Pokemon
20 - add 500 Pokemon
21 - add 600 Pokemon
22 - add 700 Pokemon
23 - add 800 Pokemon
24 - add 900 Pokemon
25 - add 999 Pokemon

You can shake the wiimote to make either an earthquake or tornado while you are inside the ranch. This will affect the Pokemon's and Wiis in the room byt with them falling down or getting lifted into the air.