Although Lanturn sounds good on paper, Lanturn is really out classed in this meta game, and finds it hard to shine. Rotom-W has a more useful ability because it allows him to bypass Spikes as well as the ever so common Ground type move EQ or Earth Power, and on top of that he has better stat distribution and is much faster. Sure his HP is what separates him from Lanturn, however Lanturn is still heavily out classed. Gastrodon and Quagsire weren't bad suggestions at all, Gastrodon being a pretty decent Pokemon in BW2 due to the over prevalence of Rain. Many would disagree in saying that it's still good, but unlike Infernape it's got an amazing ability, access to Recover, and a great typing. It's also got huge HP giving making it a great wall, and since it gets lots of opportunities to switch into Water moves, it finds itself at +1 a lot, making it an offensive threat. Problem is, it's extremely slow. My team was already on the slow side, so putting Gastrodon on my team would only make my team weaker to faster attackers.
Overall, your suggestions were fine, but my team was already hard enough to change around so don't feel bad.