Did this for the 6th time today so though I'd write some thoughts. I've done ST165, ST185 and ST205 over 15 years of ownership.
Firstly while you can do it without a hoist it is harder. The cam-belt and gearbox end mounts have to drop straight down, especially on the earlier two models. If you try to drop with any angle on the car the mounts hang up. Using a hoist we sit gearbox/engine on hip height table and lift car off. Hip height is a nice height to remove/replace gearbox.
Secondly it is technically possible to remove the gearbox (mechanics changed my ST165 that way once) without removing the engine but it must be a prick of a job to reattach the gearbox. It is $$% heavy! Stuff that.
The ST205 gearbox has a boss on the back of the block (for in-line RWD engine mounts?) towards the cambelt end that may catch on the transfer. Some gearboxes may go on easier if you grind this off.
It may be tempting to disconnect the transfer to make it easier to get gearbox on but from experience that's a bad idea.
Use a square file to tickle the spline end of a new clutch plate and shaft prior to install. Remove any burrs and put a slight lead-in on the splines.
While not really mentioned in the ST205 manual clearly the whole subframe and lower arms needs to be dropped. Not hard but be wary of alignment of the banana arms and crush tubes as they can be a bugger to line up correctly again.
If you want to lift a ST165 shell off (no hoist) an engine sitting on a trolley you have to lift the car till the exhaust pipe touches the ground. All suspension stays in place which compromises clearance and access.
Don't let the inner CV joints extend enough to pop the balls out. They are a bastard to realign...
Do the cambelt while engine is out. 30 minutes vs 4 hours (and blood loss) in-car. Your choice.
When selecting fastener types for the ST205 sump to gearbox joint the Toyota engineers were whacked on drugs. There is no other excuse. M6 with a 12mm hex head. WTF? BTW remove the bolts on the underside while gearbox is still in car.
If you have to use bolts to pull in the gearbox (to the engine) it isn't aligned right.
ST165 flywheel bolts have a shoulder that acts as a stress raiser and can cause them to fracture (when the above mentioned mechanics/monkeys do them up with rattle gun). ST205 (and ST185?) have a nice rolled taper instead. They are interchangeable. Did I mention that if that snap off once installed your clutch jams on?
On ST205 gain a little extra clearance by removing IC pump. Or it breaks...
Air con pump can be hung from brackets on radiator upper support. No need to empty.
On ST205 PS pump stays on engine. Memory tells me on ST165 it much come off. ST165 PS pump bolts are a 1/12 turn torture unless you have a decent gearwrench.
Disconnect loom plugs to ECU and body before getting car on hoist unless you like putting your back out with your legs out the window, head under glovebox. Must be getting old.
Bleed the clutch before putting the airbox back in. Doh.
Remember easiest way to fill gearbox is though the filler plug on top of the gearbox selector housing using a funnel. Don't move the selectors while this is out though.
A table to sit your tools on is much better than shit spread all around the hoist on the ground. Otherwise you spend half your time searching for that elusive 14mm socket. I never learn this.
Once you have done a GT-Four clutch you should be willing to attack anything on any car.
Hope this assists someone.