There are multiple kinds of climbers that you can make. Some are better than others and depend a lot on the other items going on the robot. The climber also relies heavily on the way the game makes you climb. A winch is the suggested way of lifting the robot with all of these ideas.

Rotating Robot

Used if you have a smaller robot that has an even distribution of weight.
Depends heavily on weight distribution and where the robot sits.
This will also depend a lot on how much you have to climb and how much space you have.

Linear

This works really well if you already have to make an elevator.
This will be a relatively heavy and slow climb.
The use of this will be most dependant on how much distance you need to climb and space in the robot.

Delivering a Hook

The hook can be delivered in many ways different ways.
You want to design the hook to not come off after being put on the bar.
This is really light and will generally look really sketchy.
This can be really quick especially if it spring loaded.
It can be difficult to control the hook depending on how it is delivered.