Actually, you could just use the timer box itself to serve as a J-box. Just remove the mechanical timer and hardwire the heater and pump. However, I think the better idea would be to use a sub-panel, and given what the loads are (the pump draws about 15A max at 220V, the heater is probably at most 3A and the SunTouch likely less than that), a 30A feeder should be sufficient. The important issue is that without a sub-panel, all wiring needs to be 10 gauge or thicker. The breakers are there to protect the wire, so if you are using anything less that 10 gauge everywhere connected on that 30A branch, you are asking for trouble and are out of code. Regardless of whether you use a j-box or a subpanel, be certain that your equipment ground is brought from the main breaker panel and separate from the neutral. So, the branch circuit from the main panel should have 4 wires, 120+ (black), 120- (red, e.g. both line wires), a white neutral and a green ground. Ground and neutral need to remain separate at the j-box or sub-panel. Somewhere in the circuit, there should be GFCI protection to the pump and heater, as they both come in contact with the pool water and a short circuit could lead to leakage of line voltage into the pool... not a good thing. So, in your current configuration, you need a 30A double pole GFCI breaker to feed the branch circuit. If you go the sub-panel route, you would need a 15 or 20A double pole GFCI to feed the pump and heater from the subpanel. Unfortunately, 2P GFCI breakers are expensive. I'm currently setting up a 60A sub-panel located at the equipment pad behind the pool house.
If you decide to use a j-box, I'd suggest just going with wire nuts. The power for the pump and heater will simply come from the j-box as both the pump and heater power will come directly from the j-box, but the control, low voltage lines that control these will come out of the SunTouch. For the pump, this would be the 4 wire cable that came with the pump so that you can screw the cable into the IntelliTouch on one side and then wire up the other side via the RS485 terminal strip in the SunTouch. The heater circuit will require a 2-wire cable that screws into the SunTouch heater terminal strip and the terminals on the heater control board. So to clarify.... power to the pump and heater will come from the j-box (or sub-panel), and the control lines to these will come out of the SunTouch. In addition, the valve acuators will be wired directly into the SunTouch. From the sub-panel/j-box, another 120 or 240V line will power the SunTouch itself.
BTW, this is how it would be done for a Pentair heater. I would imagine that the RayPak has a similar set of terminals on the controller board to turn it on/off remotely. If not, then yes, you would need a relay to turn power on and off for it.