Flat-bottomed plates can be used for all cell types, but when the number of cells is small, such as for cloning, a 96-well plate is used.
In addition, flat-bottomed plates are generally used for MTT and other experiments, both for walled and suspended cells.
U or V plates are generally used for specific requirements. For example, in immunology, when two different lymphocytes are mixed, they need to be in contact with each other for stimulation. Therefore, U plates are usually required as the cells will accumulate in a small area due to gravity. V plates are used much less frequently for cell killing experiments to bring the target cells into close contact, but they can also be replaced by U plates (after addition of cells, centrifugation at low speed).
For cell culture, flat-bottomed plates are usually used, with special attention to the material.
The round-bottomed ones are usually used for analysis, chemical reactions or sample storage. This is because the round bottom is better at getting the liquid clean, as opposed to the flat bottom. However, if you are measuring absorbance values, you should always buy a flat-bottomed one.
Most cell culture plates have a flat bottom for easy microscopic observation, a clear bottom area, a relatively uniform cell culture level and for MTT testing.
Round-bottomed plates are mainly used for isotope doping experiments where cells need to be collected with a cell collector, such as 'mixed lymphocyte cultures'.