With the gym games, I'd disagree on a couple of medium recommendations.
For Light Race: You have to treat easy as a game of Simon (in other words, in the first two repetitions of the pattern, learn the order of moves, and anticipate). I have broken 800 on Light Race on easy doing this, but it is crucial not to break your combo.
For Virtual Smash: Again a game of Simon (learn the pattern, anticipate the start of the punch). I just broke 1300 going hell for leather, so 800 is doable for most (physically, I have a fair amount of stamina but low coordination, so you can do it).
For Loop-A-Hoop: This is the hardest if you aren't coordinated. Do it on easy to avoid having to reach up for hoops more than the once. I found having legs staggered actually helped - a slightly diagonal stance if you do cardio boxing - but that comes down to personal preference. Also, don't forget to breathe!
For Stack-Em-Up: You really need to emphasise the need for greed. You need to be tipping in red blocks. Also, if you start getting triangles and circles, dump the blocks there and then - they'll only stuff you up. Definitely one for perserverance.
Retail : 25
Assassin's Creed 1+2, Bioshock, Bladestorm, Bully: Scholarship Edition, Civ Rev, DW6:E+Strikeforce+7, Elder Scrolls IV: Oblivion (w/DLC), Fable 2, Fight Night Round 3, Just Cause 1+2, Lego: Indiana Jones, Mass Effect 1 (w/DLC), NBA 2K6, Quantum of Solace, SEGA MDUC, Tenchu Z, The Godfather II, The Saboteur, Viva Pinata, Warriors Orochi 1+2
Battlefield 1943, Dash of Destruction, Doritos Crash Course, Puzzle Quest (w/DLC), Risk, Sonic 2+4:1+A1, UNO