Boss Rage: BIOFREAKS, It can only be described as pure evil and on level beyond any boss rage before it. A 7 hour grind, where at the final hour people were practically begging for Max and co to stop for the sake of their souls!
Boss Rage: Asura's Wrath, While theres not as much badass fighting game skill in it Max makes up for it by providing awesome narration to the cutscenes, plus a motivational speech preceding an awesome motivational song to accompany the beating.
Boss Rage: Mortal Kombat 9 Tower Challenge #300. Max and co. fight on for EIGHT hours, and during this time you can really see the saltflowing from their bloodstreams. After 191 attempts, with no retries (as retrying lowers the difficulty), they finally took down Shao Khan. Just some context: Max, Steve, and Kenny had to content with Goro, Kintaro, Mileena, and Shao Khan in one go without losing once. Also, this was a blind challenge, so any and all strategies were formulated on the fly.
Some credit must be given to this Sceptile player here. Using Fennekin's assist and some invincibility frames, he manages to completely avoid Max's Burst Attack and then using procedes to use Sceptile's ranged command grab to finish Max off and win the round. He then manages to win the match by winning the next round with over 400 health left. Max himself compliments the player afterwards.
BAD BOSS RAGE has Max go on a quest to defeat Sagat, and when he finally gets to Sagat, he battles Sagat (with clips from the Ryu and Sagat fight from Street Fighter II: The Movie) and succeeds in beating Sagat by landing a Hadoken on Sagat just like Ryu had done in the Street Fighter II animated movie.
A sequel to Street Fighter Legacy was made by Max. What was it? It was none other than Akuma Legacy, where Max plays as Akuma in every fighting game that he made an appearance in.