Requires 2 Dummy accounts
Open the command console: ESC > Gear Icon > Under the keyboard tab select Advanced > Check off Enable Developer Console
Press the ` button to open the console and type:
map ctf_2fort; hostname "boost"; sv_lan 0; sv_cheats 0; (I had to input this twice to be detected on my LAN for some reason)
That will create your match. Choose Pyro on the Red Team. Then type the following command:
mp_teams_unbalance_limit 0; mp_idledealmethod 0; mp_idlemaxtime 0;
Put both Dummy accounts on the other team as Medic and heavy. Bring all 3 accounts together and have the medic heal healing the heavy, while healing light them on fire.
You can also use the map cp_dustbowl and use a bot and Heavy combo. The first bot is always a medic and Dustbowl is a supported Bot Map so the bots wil move.