Pixelmon Mod

Hi, guys.

I'm looking for a command to put in command block to display the command /checkspawns legendary, cuz i'm tired to getting in gamemode 1 just for right this command, there's a way to do it ?

I think you cant
The message is display for the sender, so if you put in command block, the console will have the message (if the command work in CB (Command Block))
Do you want to use it on server or in single player ?
If you have a sponge server, you can use permission system with luckperm to do that (maybe)
Also, if you are in solo, open a local server, and enable cheat (or enable before create the world) and maybe the permission can be run without gm 1