[Solved]-R Highcharter: tooltip customization-Highcharts

Firt of all, you need to add all the data instead give only the vector (the vector DON´T have all the information to the tooltip you want). To do this you need change the data argument using the data.frame with the hcaes helper function in the mapping argument to define which variable use in every axis:

highchart() %>%
  hc_add_series(data = data, mapping = hcaes(x=date, y=hours), name = "Shipments", type = "scatter", color = "#2670FF", marker = list(radius = 2), alpha = 0.5) %>%
  hc_add_series(data = data, hcaes(date, avghours), name = "Rolling Mean", type = "line", color = "#FF7900") %>%
  hc_yAxis(min = 0, title = list(text = "Hours")) %>%
  hc_tooltip(crosshairs = TRUE)

Then you can use the tooltip argument in every hc_add_series to define the tooltip in each series:

highchart() %>%
  hc_add_series(data = data, hcaes(date, hours), name = "Shipments", type = "scatter",
                tooltip = list(pointFormat = "tooltip with 2 values {point.animal}: {point.hours}")) %>%
  hc_add_series(data = data, hcaes(date, avghours), name = "Rolling Mean", type = "line",
                tooltip = list(pointFormat = "Avg hour text! {point.avghours}")) %>%
  hc_yAxis(min = 0, title = list(text = "Hours")) %>%
  hc_tooltip(crosshairs = TRUE)