I think you might be trying to use pivot_longer() (or at least you're using the arguments for it) which does the actual pivoting, and not pivot_longer_spec(), which is part of a more advanced pipeline for manually defining a specification, and requires a special spec object:
library(tidyverse)
LomaWideSmall<- tibble::tribble(
~opponent, ~date, ~fight_1, ~fight_2, ~fight_3, ~fight_4, ~fight_5, ~fight_6,
"José Ramírez", "12/10/2013", "Win", NA, NA, NA, NA, NA,
"Orlando Salido", "01/03/2014", NA, "Loss", NA, NA, NA, NA,
"Gary Russell Jr.", "21/06/2014", NA, NA, "Win", NA, NA, NA,
"Chonlatarn Piriyapinyo", "22/11/2014", NA, NA, NA, "Win", NA, NA,
"Gamalier Rodríguez", "02/05/2015", NA, NA, NA, NA, "Win", NA,
"Romulo Koasicha", "07/11/2015", NA, NA, NA, NA, NA, "Win"
)
LomaWideSmall %>%
tidyr::pivot_longer(
cols = starts_with("fight"),
names_to = "fight_no",
values_to = "result",
names_prefix = "fight_"
)
#> # A tibble: 36 x 4
#> opponent date fight_no result
#> <chr> <chr> <chr> <chr>
#> 1 José Ramírez 12/10/2013 1 Win
#> 2 José Ramírez 12/10/2013 2 <NA>
#> 3 José Ramírez 12/10/2013 3 <NA>
#> 4 José Ramírez 12/10/2013 4 <NA>
#> 5 José Ramírez 12/10/2013 5 <NA>
#> 6 José Ramírez 12/10/2013 6 <NA>
#> 7 Orlando Salido 01/03/2014 1 <NA>
#> 8 Orlando Salido 01/03/2014 2 Loss
#> 9 Orlando Salido 01/03/2014 3 <NA>
#> 10 Orlando Salido 01/03/2014 4 <NA>
#> # … with 26 more rows
Created on 2020-05-08 by the reprex package (v0.3.0.9001)