From Halopedia, the Halo wiki
Catch This is an achievement in Halo: The Master Chief Collection. It is unlocked by earning a total of 500 Grenade Kill or Plasma Kill medals in multiplayer matchmaking. Strangely, Grenade Stick kills do not count towards the achievement. The achievement is worth 10 Gamerscore.
Players attempting to unlock the achievement should avoid playing Halo: Reach multiplayer matches, as it is the only game in the Collection which do not award either of the medals required.
From launch until the April 2022 update, players could also not progress this achievement by playing Halo 3 multiplayer matches, as it also did not award the required medals. Following the update, assists can now be earned in that game as well.