As a tae kwon do champion, Marcellino Amaro showed no hesitation in snapping off a series of lightening lightning-fast kicks and punches around the head and torso of Jay Brooks. Amaro was also willing to be tossed around and run through a series of submission moves by the smaller Brooks, a judo and jujitsu champion himself. But the Braintree resident still gets a little uneasy remembering his training sessions with boxing trainers Tim Stanton and Tim Fitzgerald. "They're the only ones that got me close to puking," joked Amaro, 40, who recently won the Worcester Classic. "But it was a humbling experience. It was great." Despite the competitive nature of their sports, the four men consider themselves good friends. And all four teach their trades at the sprawling Bayshore Athletic Club in Braintree. The instructors are teaming up to host a combat sports night at the athletic club tomorrow night from 7:30 to 9:30. Students from the three clubs...