When finalizing your rhythm section, parallel or group processing with dynamic effects will help tie all of the drums together, providing it is a well-mixed drum kit.
Using the send and return method is typically the best practice for applying effects for groups of instruments as you can send a specified dry signal and also apply a specified wet signal back into the mix without diminishing the original signal, meaning the dry signal won’t be divided as is the case with serial processing.
However, if the send and return method is not desirable then placing effects directly after the drum kit should be used delicately. With serial processing, the dry/wet control becomes the only method of allowing a dry and wet signal to be combined. Therefore, past 50% wet, the dry signal will become less and less audible. Thankfully, heavier than the usual compression is typically applied here with a minimal dry/wet mix as this group processing technique is supposed to enhance the original mix of the drum kit, not change it completely.
The compressor series such as standard, glue and multiband, are all great ways of creating a sense of cohesiveness with various drum sounds. Typically, group processing is best utilized in a parallel method as you want to blend a compressed copy in with the original mix without taking anything away from the uncompressed copy. Compressors should be relatively fast reacting with the use of quick attack and release times. The ratio should represent a higher than average value, for instance a 10:1 or 20:1 ratio. The threshold will largely depend upon the input signal but approximately 8 to 16dB of gain reduction is ideal. With settings such as the ones mentioned above largely indicates the need for using this technique in parallel, or else the drum kit will absolutely sound overly compressed and flat. A layer of this overly compressed and flat (or loud) signal combined with the dynamics of the original signal helps the drums sound loud and punchy at the same time.
Effects such as distortion and equalization will also provide a sense of oneness as instruments are passed through the same device. In any case, applying subtle layers of group processing techniques are the best practice. Mixing the rest of your project along with mastering the final product will both contribute the overall “sound” of the effects being applied at this stage. Be conservative!