While I'm not too familiar with the lower tiers, I'll do my best to help you. In your rate you clearly suggest good changes for the user's team, however you don't fully explain the changes you have made, and what they do for a user's team. While changing Golurk's ability from No Guard to Iron Fist, you could explain what the pros and cons of using Iron Fist over No Guard are. It does turn some of Golurk's 2HKOs into OHKOs, but at the same time it does risk the shaky accuracy of Stone Edge. Balancing out the pros and cons of a change is the easiest way to tell whether the change is worth it. If using x over y covers a lot of weaknesses, while being slightly weaker to something else then the change is probably worth it. Mentioning the pros and cons of a change easily informs the OP about a potential change, and fully explaining why you think x is better than y will convince the user to make said change.
When rating a team, you should also consider the counter effect of suggesting a change to someone's team. For example when you suggest a Spikes set for Cacturne, the Spikes support greatly helps Golurk like you said. The Spikes support also grant easier KOs for Golurk, meaning that maybe Iron Fist might not be neccesary on Golurk, as Stone Edge has unreliable accuracy. Maybe Golurk should run Earthquake over Stone Edge to compensate for the lack of No Guard? Maybe Golurk should keep No Guard and keep the current moveset? Maybe the user should use a different Spikes user with better synergy than Cacturne? These are all changes that you should consider as an aspiring rater, as every change in a team can interrupt synergy, and weaknesses to individual threats.
Your format is very good, one thing I would recommend is to separate your changes into individual paragraphs, as it makes it a lot easier to read. Also highlighting your changes in Bold
helps the OP to see what the changes are easily, as it stands out and immediately conveys the point you are trying to get across. Of course this is all personal preference, but I feel it makes it easier to navigate for the creator of the team, as one will not want to read lines of text.
Good luck rating!