Notes:

My edit based on the Johnny Test character Hubert "Hugh" Test from this promotional image of the show. The fire image was made by deviantART user Sunshine-Dagron.
Text sources:
"TES": Johnny Test logo
"TIC": "Johnny vs. The Tickler" title card
"U": "Johnny Susan, Susan Johnny" title card
"L": "Johnny Holiday" title card
"AR": "Johnny Test Monster Starter" title card
"HO": Johnny Test title card
"LO": Teletoon logo
"CAUST": "Johnny Moustache" title card