About your question: usually yes, it's quite redundant. If you're planning on using TS Roserade, then the last moveslot should be chosen according to the tier you're playing in. If you're using Milo in OU, then HP electric (assuming you have access to it) would be a fine choice to deal with Gyarados, while ice beam would make it a decent counter to mix-Mence, given Milotic's high SpD. If you're playing in UU, then first of all let me say that TS is an ineffective strategy, with all the grounded poison types around, and in this case you might just use HP grass (again, assuming that you have access to it) or really toxic just to hit opposing Milotic and other water types (assuming no toxic spikes from Roserade for the reason above).