For starters the Leonardo introduced a few changes to the pin layout upon its release. The ones relevant to shield compatibility (which we handle) are:
The I2C pins were changed from A4-A5 in the older Arduino’s, to D2-D3. The SPI pins which were in pins,11,12,13, as well as the ICSP headers were removed from pins 11,12,and 13. SPI can only be accessed through the ICSP headers in the Leonardo.
Switches. We allow you to switch I2C from the Leonardo's location (D2-D3) to the UNO's location (A4-A5). We also allow you to switch SPI back to pin 11,12,13 just like in the UNO. In general, with these switches you should be able to accommodate most shields. Please e-mail us if you think you have a shield that wouldn't work with our Shield-Shield.
1x Small Breadboard 2x 74HC595 1x Buzzer 1x Light Sensor 3x Jumbo RGB LED 10x LED 1x Servo 2x DC Motor 4x Buttons 2x Jumbo Button 2x Headers (40x) 3x Transistors 10x Resistors 10K 10x Resistors 1K 10x Resistors 330 1x Potentiometer 10k 1x Temp Sensor 1x Relay 2x Diodes 3x Capacitor .1uF 3x Capacitor 1uF 3x Capacitor 10uF 1x USB Cable 30x Jumper Cables Note: Although the description says, "a ton of components," please note it is not an actual Ton (2000lb) of components, but rather a figure of speech.
If you're new and just want to experiment we recommend you get the Maker Kit. It includes a lot of goodies you can play with and is quite affordable. We also recommend you get a soldering iron if you don't own one. There are a ton of options for those at affordable prices. Shoot us an e-mail if you want recommendations :).
The Shield-Shield was designed specifically to work with the BLEduino. That means that it is not compatible (as far as we know) with any other board. However, that doesn't mean we won't release Shield-Shields for your favorite boards in the future ;).