Summoning Expressroid will return 2 cards from your graveyard to your hand, which is usually because they are used for fusion. Use this together with Supercharge so you can draw 2 more cards. This will give you at least 4 cards, and +1 during your draw phase.
Having more card advantage can be useful if you can take advantage of it with cards like Wonder Balloons. You can use Wonder Balloons to discard 2 "roid" monsters, special summon expressroid and discard 2 roid monsters again on your next turn, which will reduce all monsters your opponent controls by 1200. Rising Energy can be used to protect expressroid or other monsters you control.
Since the effect activates whenever it's summoned, you can normal summon it to recover 2 roid cards, attack into your opponents monster to destroy itself, and special summon it back to the field to get more cards. This is only if you have plenty of roid monsters in the graveyard.
You can use the "roid" monsters as fusion materials for Chimeratech Overdragon since they are all machine type monsters. Having more fusion materials increases its attack and number of attacks it can do, which can be good in an OTK deck. You will need at least 1 Zwei in the graveyard to be able to do this and Cybernetic Fusion Support, as well as clearing your opponent's backrow so Chimeratech won't get Floodgated or negated.