The Basic type only goes to lands, so take them off all your creatures. Also don't put trample on everything, it's a rather strong creature ability :U Also as a good rule of thumb, a creature should usually have a combined P/T equal to twice its CMC or less unless it has additional costs or some ability that actually makes it a weaker card, and even lower than that if it has other useful abilities.
+ Agnaktor: 4-cost for a 6/5 trample with abilities is kind of cheap, you should decrease its toughness a few points to fit red more. Second ability is weird, you'd be making up a new counter just for that, and on top of that red creatures don't really care about toughness. It also doesn't fit red in general, since red is about burn and punching the player until they die, not sit around while building up big creatures, so you should make the second ability something like 1R: Agnaktor gets +1/+1 until end of turn.
+ Brachydios: Way too broken. Even if it's a plain 7/6 with trample without anything else 5-cost is too cheap. Slime counter ability is too broken, that's 3 damage a turn you can save up and unload on something later when you want to. Also, you need to say exactly when it gets slime counters (e.g. at the beginning of your upkeep), and what it can deal damage to (e.g. a creature it's blocking/being blocked by). Example:
+ Giginox: No. The brokenness is off the roof, especially with the infect. Lifelink doesn't fit. Infect tokens are taboo, since 1) they're basically suicide tokens that your opp needs to sacrifice their creatures/mass removal on or take an equivalent of 2 unhealable damage each, and 2) it makes you more likely to land an infect hit, which is really strong (see also: the trainwreck that is Blighted Agent in any deck that can pump). Lifelink just makes it more brutal. This needs a massive nerf, starting with taking infect away.
+ Lagiarus: Seeing no reason to have white cost on this. Haste and trample are the two thing you almost never can find in blue, and they're also very rare in white. Also has a too high P/T for the cost, trample notwithstanding.
+ Tigrex: Okay, you really went all-out on this one. Trample flying is a really broken combo, and most creatures that have both in official material have P/T that are each only at most 3/4ths of their CMC. This is already too strong for bloodthirst and battlecry, and you're supposed to state a number for bloodthirst also. Annihilator is an extremely strong keyword, and things that have it have very few other abilities (or is something with an outrageous mana cost that is supposed to be a "GG YOU LOSE" as soon as they are played and not countered). The activated ability should say 3RW instead of 2W1R, and really any creature with stats this high (never mind anything else) doesn't deserve to have its own double strike ever, no matter how much toughness you subtract from it (and really, It already kills a whole bunch of things on the first hit, who cares about toughness)