Hmm, I have quite a load here, but I can see these the most for myself:
Gradius-2's Bigcore MK-II boss fight arranged in Gradius-V (for whenever I face a powerful enemy),
Intruder - from Raiden 3,
Simulation Level 01 (Enemy Launch Base) - From Raiden-Fighters Jet (keeps me dancing for some reason, maybe it's fast pace?)
Great Sea Power - from Thunderforce-IV (yet another epic feel from it)
War-like requiem : Vs. Final Boss - TF 4 (for some reason, I defeated Strife in SC-3 listening to this and flowing with the rhythm of the song...)
Vs. Cherub-Purple - from Thunderforce-VI (an epic feeling... with a hint of grace when fighting)
Vs. Orn-Emperor, Type-2 - Thunderforce 6 (Love the tension and fast-paced feeling, suited for a Semi-Final battle)
High-Class Competition Battle - From R-Type: Final (another epic feeling when in a dark place)
Swipe of Sword - Devil May Cry - IV (another graceful feeling)
Ragnarok (Vs. The Despair Embodied) - DMC2 (It aided me in two near-impossible boss fights, suited for yet another part of the Semi-Final battle)
Vs True Sigma - Megaman-X 4, 7 & 8 (well suited for a final battle)
Battlefield - from Golden Axe PS2 arrange (it's traditional)
Stage 5-A2 - from Neo Contra (just drop dead plain cool! Try listening to this while in the meadow under the full moon)
Stage 5-MidBoss (I listened to this while fighting a few times, check my Y-T account to see what I mean.
hmm... did I bulk this?
Hey, Smash! Try adding this boss theme song to your RPG while fighting against Eggman somewehre!